i had a similar idea regarding card games with the bosses, but i neither have the time nor ideas to fully develop it
i'd say my entry is more action oriented; i'm basing the core gameplay heavily on the sega genesis game bonanza bros. if you're unfamiliar, it's a game where you play as a thief who steals various treasures from various places under a certain amount of time. i've always wanted to see how well the game would scale to a 3d environment. how i've got it planned out is that you start off with a limited amount of ammo that doesn't replenish throughout the run. you can't kill enemies, but you can stun them for a bit, making the collection process ever so easier. at the end of the game, you'll receive a time bonus depending on how much ammo you had left, so there's a strategic element to ammo conservation if you wanna make certain levels easier/get a better time.
i've had plot stuff in the back of my mind, as i'd like to flesh out the game after the jam period, although i'm uncertain if it'll happen.
i like what you're planning with your entry though, would love to see where it goes. as for any sort of recommendations, maybe you could add a stealth mechanic to the game? you could get extra information by eavesdropping, access secret rooms, etc
cheers
i was not familiar with bonanza bros, so i searched for it on youtube. seems pretty fun actually, art style would take a bit for me to get use to.
though im curious how the vampires and stuff come into play, special abilities and that sort of thing.
stealth is a good idea, but eavesdropping would be pretty hard to implement corectly without voice acting, as having something text based would be easily readable.... unless, i could do a sort of word coruption system, so after entering earshot range. the charactors get corupted and replaced with a random charactor as they charactor speaks and the rate at which they randomly get corupted drops as you get closer to t them, though that might mean a more scripted event system where they talk about certain things at certain times, and im not too fond of that as its content that can be missed, with a gamejam its pretty important for people to see as much content as possible because of the limited development time.
secret rooms are good but only if there is something important in it, so ill try my best but with the time limit it might be a bit on the light side.