This idea kind of builds on various elements of other ideas I've had, which is shorthand for "after ripping off so many other game designs for ideas, I'm now resorting to ripping off myself for ideas". Only pretend I didn't say that. I'm innovating. That's what's going on here and that's all that's going on here.
We zoom out so our token party of adventurers are shrunk down and we (the player) are able to see a large cut-section of the dungeon the adventurers are about to explore. Now, the gameplay's focus (and much of the humor) comes from the fact that these entirely computer-controlled adventurers are dumb. They will wander into pretty much any impossible situation without a thought and quickly perish. They do have some amount of combat ability and magic between them, but their ability to apply it effectively is limited. So, as is usual in these scenarios, it's up to you to try and keep them out of trouble, while still procuring for them enough treasure to make the entire ordeal worth it.
The adventurers will level and haul treasure around like they do in any other hack and slash, but generally their role is minimal. You, the player, control a guardian deity of sorts that is using its diminishing divine powers to keep the small gaggle of true believers alive long enough for them to start influencing others and restoring your strength. The fact that these morons are the only worshippers you have, who in actuality only wrote your name as their patron deity on their Adventurer License application forms to avoid requiring a referral from any of the established churches of the land, is causing you some grief. You have some limited amount of godly powers in this role and can directly influence parts of the dungeons for the benefit and safety of the goonish heralds you're stuck with. These powers include forcing stone passages to open/close, increasing the water levels, flooding chambers with poisonous gas and other powers based on any given dungeon's natural attributes. A volcano dungeon (I always use a volcano as an example for some reason, strange huh?) might allow you to raise/lower the level of deadly lava, but only while you and the adventurers are in that dungeon. An ice dungeon wouldn't have lava, so you can't use the same power there. That's just an example, the point being is that every new dungeon will have its own tricks and related powers, and it'll be up to you to explore and experiment with what you can do before the adventurers tumble along into whatever trap is set along their path.
Which brings us to the core gameplay. You have to ensure that the adventurers get into as few traps and fights as possible (they can survive some, granted that the traps aren't too deadly and the monsters are well in their league) while acquiring as much treasure as possible (it'll be important for influencing others to join your religion, boosting your power reserves with their prayers). The best way to do this would be to keep the adventurers out of trouble while eliminating the monsters in the dungeon with your powers. If possible, think of ways to eliminate the monsters guarding some treasure without also destroying or blocking off said treasure, then allowing the adventurers to come across the now unguarded booty. Keep in mind that the adventurers have no idea that you're actually real (why would they? They used your name as a convenience) and that if a dungeon appears to be blocked off to them (when really it's just you temporarily blocking the passage to protect them), they'll leave. Similarly, they'll panic if you see your powers in action or somehow find themselves trapped (which might be something else you'd consider doing if you didn't want them wandering off). This panicking could cause them to run around aimlessly and be even dumber than usual for a while. While every attempt will be made to keep your adventurers lovably stupid, there will be some situations where they might just end up annoying you slightly by doing something unbelievably idiotic that they end up destroying both themselves and your progress in acquiring a clergy. Hopefully this kind of thing can be kept to a minimum.
Like my previous Lemmings-ish Hack-N-Slash game, what I'm really interested in messing around with is scale. So giant monsters will end up really big, appropriate to the scale between them and the heroes. No simply using human-sized enemies to keep to conform to a specific sprite size, no sir. Monster AI, too, is something that needs a strong focus. The game needs to repeatedly demonstrate that most of the monsters are actually far superior in mental agility than the dumb treasure-hungry humanoids invading their homes, which is why your input is so necessary to keep them alive. You have no qualms about destroying any kind of lesser life, as a god and as the player, so feel free to wipe out whole civilisations of sentient, peaceful but potentially-dangerous-if-riled monsters to keep your followers alive long enough to demonstrate that having you as a patron god might not be such a bad thing. In fact, if other, slightly more competent adventurers start taking you on as their patron god, you can go help them and simply abandon your current bunch of dumb assholes to the inevitable grisly fate that they've dodged for so long. I guess I should note that the deity you're controlling is not necessarily the benevolent type.
