It’s a Tower Defense Tuesday: Incursion 1 & 2

Since Clicker Heroes isn’t exactly a game that you actively play (at least not for more than a few minutes at a time), I’ve run through both of the Incursion Tower Defense games.

I’m not sure how I feel about them. I mean, I enjoy them, but they don’t bring anything new to the table. Yet despite not bringing anything new to the table, for the most part they are able to synthesize the pieces they borrow from into something that’s colorful and entertaining.

I’ll go right out and say “they’re no Kingdom Rush”, but the elements that are borrowed from Kingdom Rush are a big part of what makes them enjoyable.

It uses the common rock-paper-scissors mechanic that is similar to Cursed Treasure, with archers (light), soldiers (heavy), and mages (magic, duh), with light attacks being strong against magic armor, heavy attacks strong against light armor, and magic attacks strong against heavy armor. The most striking difference between Incursion and Cursed Treasure (towers only, no ‘units’) or Kingdom Frontier (towers and ‘units’) is that, like Demon Rift, towers ONLY create units. Unlike Demon Rift, however, towers can create mixed units (one tower can have an archer, a mage and a soldier, though there are disadvantages to that approach; archers & mages are terrible in melee until they reach high levels, so you want to keep them off the roads, usually too far away for any soldier grouped with them to auto-engage).

The difficulty of having your mages and archers being physical units rather than a tower is, like your soldiers, they can be killed. This is a particularly bad problem with the first game; since you couldn’t set target priorities, all units would attack the enemy farthers along the route, regardless of what was happening around or to the unit. Therefore, the most frustrating enemies were the archers, who would pick off your guys who were fighting against baddies further along the path, and Necromancers, who would continuously raise skeletons who gave you no money and would prevent you from ever getting to the Necromancer unless you mucked around with your deployment flags. Fortunately, this was fixed in the second game, which makes it a much easier and less frustrating experience.

The second game gives you a couple unique characters to play with, which also really helps in dealing with those obnoxious enemy archers and spellcasters. So much so that the fact that you can specifically target enemies with any of your troops doesn’t come into play nearly as much. The heroes (particularly when you’re given two) make things pretty dynamic.

The cool thing about the Incursion games is that each level has a unique thing going on, whether it’s an ally with a strange or difficult method of activation or an element of chaos, some monster who will kill everyone around it willy-nilly regardless of whether it’s your guy or a bad guy.

The look is similar to Kingdom Rush (one might go so far as to say a “borrowed aesthetic), which isn’t a bad thing. It plays similarly, though perhaps less frenetic. There’s kind of a strange difficulty curve in second game, where the middle few levels are extremely difficult, while the last few levels are fairly easy (last two levels I got perfects on the first try). The goblin chaingun IS gamebreaking and you WILL get a perfect against the final level if you stock up a couple of them. You might find yourself frustrated by how much slower you’re upgrading things (you are essentially having to upgrade 3 different towers per location), but it’s an understandable game balance issue. You’ll eventually figure out that a bare minimum of soldiers in the right places combined with as many ranged units as possible tends to work out best. At least in the second one. I might need to give the first one another go and test things. I feel like the first game had more waves of quick moving medium health regenerating monsters that had to be stopped, while the second one focused more on slow high HP high damage giants with a range of abilities. You needed lots of troops to slow down the former, while it was best to stay out of the latter’s way and just wizard zap and arrow them.

I won’t say that the Incursion games are my favorite TDs, but if you enjoyed either Kingdom Rush or Cursed Treasure, they’re worth checking out.  You can play both for free on Kongregate.

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Siege of Alfort (Morgansfort): Tower Defense Style – Prep Work Part 4, Factions for Flavor

This is going to be a briefer post than the others, largely because it does not involve number crunching. In fact, the purpose of this portion of the prep work is to reduce the amount of number crunching.

The battle and conflict as it’s statted out and scripted in the previous posts does not reflect the battle as a whole. While the 200+ Hit Dice of evil elven undead represents a formidable force more than capable of overwhelming the PCs and the fortress’s defenses, it doesn’t connote that “army” feel. It’s not big enough. Now, admittedly, this is going to be window-dressing, but it will certainly help the battle feel bigger.

Other factions –
Imperial expeditionary force – I’m not sure what all will have happened between the time I am writing this and when the encounter will happen, but one possibility is that Portsdam is destroyed by an earthquake. Whether that happens or things have just been so bad in the colony that word has gotten back to the empire, let’s say that an expeditionary force has landed north of Alfort and is on its way. Maybe 2000 strong, this force, while small will certainly distract a chunk of the Elf King’s undead army, preventing it from bearing its full brunt against the fort. If the PCs haven’t cleared out the Zombraire’s estate module, this force will probably be ambushed from west and arrive significantly weakened and unprepared to stand against Caelden’s army.

Eastern Goblin Coalition – The Southeast and Northeast goblin tribes have formed a military alliance. They understand that a limited human presence in Alfheim is preferable to the land being awash with undead elves. Sometime between now and when the battle is run, the PCs will be presented with a chance to dislodge the Northwest goblin tribe from the Old Island Fortress (if the PCs don’t go along with it, the goblins will later take this on their own). The Old Island Fortress will be used as a staging ground for the eastern goblin tribes to lend their support against Caelden’s army.

Northwest Goblin tribe – I’ve retconned my setting a bit to eliminate Orcs as an indigenous people of Alfheim; while Orcs are there, they’re mostly imperial mercenaries (note to self, the imperial expeditionary force should be comprised largely of Orcs). That said, I’m rewriting Starisel’s dungeon to be inhabited by goblins (with Orc stats) instead of the orc tribe. These will be part of the same tribe who were trying to take over Malek (the Nameless Dungeon) until they were slaughtered by undead. If the PCs can reconcile with these goblins (successfully run Cave of the Unknown), there is a good chance that they might be willing to commit to fight against Caelden.

So we’ve got a Battle of Five Armies, here, a perfect climactic fight for the campaign.

To incentivise the players to gather these allies, I might even take away the last two waves via some sort of plot-flash.

Siege of Alfort (Morgansfort): Tower Defense Style – Prep Work Part 3, Enemy Combatants

So, this part is going to take some tweaking, and maybe even some test runs, so these numbers are far from final.

Let’s have a run-down of the various undead we have to work with:

Skeletons 1 HD 20′
Zombies 2HD 40′
Ghoul 2HD* 30′ (paralysis)
Wight 3HD* 30′ (Level Drain)
Wraith 4HD** 40’/ (Level Drain)
Mummy 5+1HD* 20′ (disease)
Spectre 6HD** 50’/100′ (Level Drain x 2)
Vampire 9HD** 40’/60′

The bulk of the monsters are going to be skeletons & zombies, low hit dice monsters who should probably be ignored, if possible, in favor of the bigger baddies coming through. So, let’s come up with some ground-rules for how each of these monsters operates:

Skeletons – move along the scripted path. Remove 1 HD of defense and ‘go away’.

Zombies – move along the scripted path. Remove 1 HD of defense and ‘go away’.

Ghouls – move along the scripted path. Remove 1 HD of defense and ‘go away’ so long as there are at least 3 HD of defense present; otherwise, remove 1 HD of defense per round until no defense is present and continue along path.

Wights – move along the scripted path. Remove 1 HD of defense per round until no defense is present. When no defenders are present, continues along path.

Wraiths – move by flight through walls & buildings towards currently targeted zone. Remove 1 HD of defense per round until no defense is present. When no defenders are present, continues along path. Once, Nuromen may use “Sleep” to allow the elimination of 2d4 HD of defenders.

Mummies – move along the scripted path. Remove 1 HD of defense per round until no defense is present. When no defenders are present, continues along path.

Spectres – Considering their special ability of creating new spectres, I’m highly considering omitting these guys. We’ll see. moves by flight to towers, eliminating tower & rampart defenders. Remove 1 HD of defense per round until no defense is present. After reaching zone 6, will enter the chapel.

Vampire – moves along the scripted path. Remove 1 HD of defense per round, though continues along path without stopping.

Here’s a sample elven army.

60 skeletons
30 zombies
15 ghouls (accursed elves)
5 wights (undead elf knights)
4 Wraiths + Nuromen (undead elf mages)
4 Mummies (undead elf clerics)
2 Spectres (undead elven princes)
1 Vampire (Caelden, lord of elves)

Wave 1
10 skeletons
10 zombies

This wave might even be completely turned.

Wave 2
10 skeletons
5 zombies
5 ghouls

Some of this wave might be turned; I expect this to be the first wave to do some damage in zone 1.

Wave 3
10 zombies
5 ghouls
1 wight

This is something of a wakeup call with the wight. If the heroes are fighting from the walls, it should be apparent that someone is going to have to go down and deal with it.

wave 4
5 zombies
5 ghouls
2 wights

Things being in earnest now. Clerics within the castle will likely have run out of turning, and the wight’s level drain could be a serious problem.

wave 5
10 skeletons
2 wights
Nuromen

Boss wave. While the skeletons just march onto reduce various zone HD, Nuromen will be casting spells and with the two wights who accompany him, he’ll be pretty tough, even with his limited HP.

Wave 6
10 skeletons
2 wraiths

Consider this a sequel to wave 5, but at least these wraiths aren’t casters.

Wave 6
5 skeletons
1 wraith
1 mummy

The mummy is going to slowly tank his way through the defenses.

Wave 7
1 wraith
2 mummies

Ditto.

Wave 8
10 skeletons
1 Mummy

Consider this wave a reprieve?

wave 9
5 skeletons
2 Spectres

If things aren’t already really bad, this may be the end of things. The heroes might seriously consider running at this point.

Wave 10
Vampire

The vampire more or less makes a Beeline to the bank, the apartments, the chapel, then the keep. He’s got important things he wants in those places.
Goals:
Ultimately, the castle is meant to fall. The main goal the heroes should have is staying alive or maybe stopping Nuromen (wave 5). Anything after that point ought to be gravy, though they should probably try to either escape through the Chapel Tunnels, the Keep Tunnels or any other possible means.

On the off chance that 8 waves are defeated before the chapel falls, I would consider this a decisive “win” for fort, if it weren’t for those pesky spectres. While Caelden might ‘retreat’, there would be a ton of dead that would need quick sanctification or things could easily be worse than before, in which case, the fort falls anyway. If the heroes manage to somehow defeat all 10 waves, Caelden likely retreats to lick his wounds. In this final case, he’ll probably be treated like any other vampire and sent to his lair (I might stick him in the Gibbering Tower) to be hunted down.
Up next, I’ll detail the tactical scenario leading up to the siege.

Siege of Alfort (Morgansfort): Tower Defense Style – Prep Work Part 2, Scripting the Scenario

To make this Tower Defense style scenario work, I need to come up with a basic script for the battle, including the strategies of the NPCs invovled, to faciliate the overall flow of the encounter.

For ease of play, all monsters share initiative and take their turn first, followed by defenders ranged attacks, then the PCs’ actions.

“Zones”
1 Main Gate
2 Behind Main Gate
3 Below Tower 2
4 In Front of the Stables
5 In Front of the Bank
6 In front of the Chapel
7 Beyond the Chapel
8 Between the walls
9 The Green
10 The Keep

I’m renaming the towers to make it easier to follow.
“Towers”
1 – Tower 18
2 – Wall between Tower 18 and Main Gate Main Gate Tower
3 – Main Gate Tower
4 – Wall behind Main Gate Tower
5 – Wall between Main Gate and Tower 2
6 – Tower 2
7 – Wall between Towers 16 and 2
8 – Tower 16
9 – Wall between Tower 22 and 19
10 – Tower 19

Important note: “Towers” may or may not hold their fire against skeletal or aetherial undead; regardless, their attacks have no effect. Special rules will be described later for ‘special’ undead (including leaders), who MUST be fought by the PCs.
Phase 0:
The enemy army approaches; this gives PCs and the south towers opportunities to fire on enemy mobs.
Phase 1:
Someone has answered the Call of Caelden, and, betraying the garrison, lowers the gate.

Ranged attacks from south wall concentrate on gate & road.

Phase ends when 8 HP of monsters enter area 1.
Phase 2:
Undead focus efforts on entering area 1 and moving beyond to zone 2.

Towers:
1 – moves 4 to 2; after 3 rounds, targets road.
2 – moves 2 to 4; after 3 rounds, targets monsters entering zone 2.
3 – pours oil down murder holes 2 rounds, fires through on enemies below or on road.
4 – targets zone 2
5 – targets road

Phase ends when zone 2 is overrun.

Phase 3:
Undead move along course toward Zone 3 under Tower 6.

Towers:
2 – targets road
3 – Priorety: murder holes, zone 2, then road.
4 – targets zone 2
5 – targets zone 2
6 – moves all to 7, holds until phase 4

Phase ends when zone 3 is overrun.

Phase 4:
Undead move toward zone 4. Garrison has built blockades in front of where Taramedes house stood.

Towers:
2 – targets road
3 – Priorety: murder holes, zone 2, then road.
4 – targets zone 2
5 – targets zone 3
7 – targets monsters moving from zone 3 to zone 4

Phase ends when zone 4 is overrun.

Phase 5:
Undead have overrun zone 4.

1 out of every 2 HD of monsters will enter the stable (area 3). After 8 HD have entered the stable, from east door, they will emerge from west door. All animals & npcs in the stable will have been eliminated, and the stable will begin to burn.

Other monsters will continue moving toward Zone 5

Towers:
2 – Targets road
3 – Priorety: murder holes, zone 2, then road.
4 – targets zone 2
5 – targets zone 3
7 – targets zone 4

Phase ends when zone 5 is overrun.

Phase 6:
Monsters have access to the east plaza area. Garrison has attempted to blockade the chapel street, zone 6.

Monsters will move towards any accessible buildings. 4HD worth of monsters will destroy buildings they enter; unlike encountering “garrison”, this does not eliminate the monsters.

Destroying these buildings will be a priorety (except in my campaign, the building designated as the residence of the villain).

After these buildings are destroyed, monsters will focus on zone 6, the alley in front of the chapel.

Towers:
2 – Targets road
3 – Priorety: murder holes, zone 2, then road.
4 – targets zone 2
5 – targets zone 3
7 – targets zone 4
8 – targets zone 5

Phase ends when three buildings are destroyed.

Phase 7:
Monsters attack zone 6. Towers begin to route.

Towers:
2 – Targets road
3 – Begin moving toward Tower 9, arrives in 12 rounds.
4 – Are killed
5 – Are killed
7 – Begins moving towards Tower 9, arrives in 12 rounds.
8 – Begins moving towards Tower 9, arrives in 11 rounds.

Phase ends once Zone 7 is overrun.

Phase 8:
Once zone 6 is overrun, monsters with more than 2 HD will enter the chapel. Other monsters will attack Zone 7

Towers: tower units that are able will shoot at targets of opportunity while moving towards Tower 10.

Phase 8 ends when 10 HD of monsters enter chapel and Zone 7 is overrun.

Phase 9:
Monsters attack Zone 8.

Towers:
Towers 9 & 10 will attack monsters in zone 7.

Phase 9 ends when monsters overrun zone 8.

Phase 10:
Monsters attack zone 9.

Tower 10 attacks targets of opportunity.

Phase ends when monsters overrun zone 9.

Survivors may escape via tunnels to somewhere Northwest of the fort along the coast.

Next time:
Figuring the monster hordes and possible Win conditions for the heroes.  (Important to note, that if things get past phase 5, the battle should be, for most intents and purposes, lost, and hopefully the heroes will realize this.  Then again, heroes love fighting to the bitter end.)

Siege of Alfort (Morgansfort): Tower Defense Style – Prep Work Part 1, Statting Defenses

(Download Morgansfort to follow along.)

First of all, I need to figure out roughly what Alfort’s (Morgansfort’s) defenses are and translate that into numbers that can be used in a Tower Defense style scenario.

So, what I’ve done is figured out the total Hit Dice of the fort’s defenses. All told, there are 129 Hit Dice worth of garrison, 134 if we include the Baron/Castellan/Lord. This doesn’t mean there are 134 defenders (it’s actually closer to just over 100) who are in the garrison nor does it mean that there aren’t various level 1 and level 0 persons in the town who might be caught up in the fighting; this is just the number we’re going to use to determine the Keep’s “HP”, for lack of a better term.

One interesting difference between Morgansfort and the Keep on the Borderlands is that most of the guard are not specified to be carrying ranged weapons, though the notes indicate the presence of such weapons in 1, 2, 16, 17, and 22 (all various towers). Though there are none mentioned present in 19, the central tower, one should assume that anyone heading there will have passed someplace that they can grab a bow or something.

Rather than have a fixed HP for the Alfort/Morgansfort, various key points in the fort will have strength represented by the number of HD of garrison present; the fort will fall to the attacker in successive waves as the defenders lose ground. Each HD of monster (regardless of the damage they will have taken) will remove 1 point from a location’s defense.

Now, how to figure out where the defenders are? Well, the notes for Morgansfort explain that the main garrison force is comprised of 8 squads of 11 of the 88 footmen (these do not include the “Knights”, and all told account for 93 of the defense’s 134 hit dice). Now, the Knights will be around doing their own thing with other defenders OR it will be assumed that they’re among the defenders adding to the numbers of whatever location they are represented by; since none of these individuals have been characters in my campaign, it will be unnecessary to adjudicate their deaths, but if you’ve been running Morgansfort by the book, you might consider being more particular about who is where.

Since Morgansfort can really only be attacked from the south and the west, We can assume that 22 (North central tower), 17 (Northeast tower) and 16 (East central tower) will be relatively undefended unless the situation changes. Men in towers will get ranged attacks at attackers but not count towards the “HP” of a zone unless they get down.

So, let’s talk defense zones:

1-main gate
1a- behind main gate
2a- below tower 2
3a- in front of the stables
6-the Square is big enough I think it worth breaking down
6a- in front of the bank
6b- in front of the chapel
6c- in front of the inns
6d- in front of the warehouse
15a- the plaza south of the chapel
19a- the avenue between the central wall and south wall
20- the Green
25- the keep

That’s a lot of areas, but there are a lot of HD to be spread across it. Truth be told about 6, however, the spot in front of the bank, trader and herbalist’s is pretty do or die, so anyone defending the square would make this spot a priority; I’ll assume that if this area falls, there’s nothing but archers in the 16(East Tower) to keep baddies out of those buildings. 6 can be condensed, therefore, to some key strongpoints set up by the bank and in front of the street the Chapel is on.

So that leaves us with (no longer using the module key)
1 Main Gate
2 Behind the main Gate
3 Below tower 2
4 In front of the stables
5 In Front of the bank
6 In front of the Chapel
7 Beyond the Chapel
8 Between the Walls
9 The Green
10 The Keep

That’s still going to be a lot to defend. Let’s see if we can plug some numbers in.

“Zones”
1 Main Gate – 8
2 Behind Main Gate – 10
3 Below Tower 2 – 8
4 In Front of the Stables – 15
5 In Front of the Bank – 20
6 In front of the Chapel – 8
7 Beyond the Chapel – 10
8 Between the walls – 8
9 The Green – 10
10 The Keep – * We’ll come back to this.

That’s 97 HD worth of defenders. Part of this number assumes that defenders from the northern towers have descended the walls to join the fighting.

“Towers” (These WILL use the module key)
1 Main Gate – 4
Between 18 and 1 – 2
Between 1 and 2 – 2
2 – 4
16 – 4
18 – 4
Wall between 22 & 19 – 4
19 – 4

So, there’s 28 HD worth of firepower coming from the various towers. We’ll say that the remaining 9 HD consists of the Castellan and 4 personal guards remaining with everyone in the Keep, perhaps ushering them out of tunnels somewhere to safety.

Up next, I’ll write up a short script of how the scenario will play out, after which point I’ll try to figure out how many undead and in how many waves should they come.

Dropped some coin on the full Defender’s Quest

I can’t think of any better way for a game to say “Welcome to Paid Content” than having a Red Dragon join your party. Ironically, the Red Dragon may be the weakest member of my party, given how hard I was grinding to get 3 stars on all of the Demo missions. One of the things I worried about was the subsequent missions might be too easy because I’d gotten my party up to around level 16 or so; fortunately those fears seem to be unfounded. Yeah, the 1 star missions will probably stay a cake-walk for a bit, but 2 star missions are challenging and 3 star missions are, at the moment, impossible. I can’t imagine how high level I’ll need to be to kill that stupid golden sheep.

I don’t know how much more I’ll be blogging about Defender’s Quest; most of the blowing away has already happened, and I’ve said what I think is worth saying about the system. Still, thought I’d give it one last plug this year. Depending on how my TD style D&D encounter goes, I’ll maybe add some additional remarks.

In the meantime, check this livestream going on now about Tabletop games.

Defender’s Quest: A Review and Conclusions on Integrating Tower Defense into Tabletop RPGs

As I mentioned the other day, I may have finally found a game on which I could model a Tower Defense-style D&D encounter. The game is Defender’s Quest and the first half of it is available to play for free on Kongregate.

Like your typical Tower Defense game, the main objective is to stop the mobs from getting from point A to point B. In Defender’s Quest, however, point B is the main character, who is some combination of mage and psionicist and is the party leader.  Instead of Towers, you strategically place party members along the path to prevent the mob from killing the mage.

One of the things that is interesting about the use of ‘party members’ is how they are identical mechanically and functionally to towers in terms of gameplay, but the feel is very different. Because each tower is a named, customized and equipped individual, you have more attachment to them (especially the first characters from any given class you gain access to, as they are featured heavily in the cutscenes) than your typical arrow firing tower.

A significant difference between this game and other Tower Defense games is that in any given mission, you are restricted to your current party members; you can’t just buy more towers in the middle of a mission to pad out your defenses. You CAN, however, generally place all of your towers (party members) at the beginning of a mission, though it is not necessarily beneficial to do so.

Rather than gold to buy and upgrade towers, the party leader (here’s where the psionicist part comes into play) uses psi points to deploy party members on the map and upgrade them, which both increases base stats and unlocks the use of any additional abilities that party member has access to. This psionic upgrade is a temporary upgrade, lasting the mission’s duration only. The true upgrading/scaling comes between missions when party members gain levels, gain access to new abilities through a development tree, and are equipped. Additionally, you have the opportunity to recruit new party members in towns to help deepen your ranks, though these green recruits will be of limited usefulness until they get some kills under their belts.

Because Defender’s Quest attempts to combine tactical RPG with Tower Defense, the way that combat is handled is slightly different from most Tower Defense games. In a game like Kingdom Rush or Demonrift, melee exists primarily to block paths, either slowing mobs down while towers get kills or doing the killing themselves. In Defender’s Quest, there are two distinguishable mob types (not unit types, there are many different units): monsters who are determined to make a bee-line for your mage and monsters who will pause for a moment to take a swing or shot at whomever is near by while making a bee-line for your mage. Unless they are heavily armored and have massive damage resistance, like some of the Revenant Knights, the former are more of an annoyance than anything. The difficulty arises from the mobs who stop to take an 8-10 HP swipe at your swordsmen or spit gobs of acid at your ranged fighters. You have some magic to patch your companions up with, but that damage can add up quick. So unlike most tower defense games, your towers can “die”. You can redeploy them with the psionic points you earn for killing enemies, but they are placed back on the map at minimal strength without any previous psionic boosts you may have given them.

Like other Tower Defense games, you can “sell” towers, regaining some of the psionic energy invested in them, and be able to put them elsewhere on the map. Again, though, the difference is in how it feels despite mechanical similarity; your party is sacrificing certain tactical advantages to try to gain others. There is a boss fight against a powerful undead where your strategy is to deploy and redeploy your melee fighters further and further up the path until you can fully wear him down.

Rather than the abstract leveling of the player in terms of overall points to spend on your meteor attack or general tower bonuses or whatever you typically find in fantasy Tower Defense games, you level in a concrete manner alongside your party members, because you are represented on the map by the main character mage complete with spells and HP just like your companions. It’s this mage character who is giving boosts to party members, casting spells to aid them, and zapping the monsters who get past them with lightning bolts rather than a disembodied player power. The in-game justification for the character’s use of psionics to deploy and boost the party’s strength is a bit silly; I think that the maps and all of the battles may actually be some sort of abstraction or they’re in the shadow realm where they can hurt revenants or something ridiculous to try to explain a mechanic that works amazingly well without requiring an explanation. Whatever, it’s great.

Given enough time, this is probably close to what I would’ve come up for making a D&D Tower Defense scenario, but since it’s right here in front of me, there’s no reason not to just steal what is so close to perfection.

The main thing I can think of to change would be using basic movements rather than re-deploy and not using psionic points for everything; basically use D&D for that (duh). In Defender’s Quest, monsters that attack the party members aren’t stopped, rather they stop, attack and keep going. In D&D terms, this would be move into melee, take a round of attack, make an attack, receive a round of counter-attack, move on. It doesn’t have to be that rote, though; borrowing from Kingdom Rush, while one or two monsters stay engaged with melee characters, other monsters break through.

Ultimately, I think the main thing needed to make such a scenario work is a combination of a plausible goal for both sides and workable map.

The goal part is difficult but flexible. If defending a town, you can base outcome based on something like how many hit-dice worth of monsters getting past is beyond what the townsfolk and constabulary can handle on their won. Or how many of certain goods can be stolen without it being disastrous. Goals can be keep the town guard from being overrun, keep x trade goods from being stolen, keep monsters from preventing wizard from casting a spell, keep monsters from carrying off an important person/thing, so on and so forth. The really hard part will be making a map. You’re going to want a big map and probably lots of counters. You can’t do this without lots of counters.

If I can find some butcher paper, I just might see if I can make a big climactic tower defense style battle for the end of Shadow Over Alfheim.

Oh, yeah, and when I finish the demo, I’m probably going to go ahead and buy the full game of Defender’s Quest.