amber blade
My idea is a large facility that holds a bunch every monster in the game (besides the ghost lady and all un-killable monsters)
The facility itself would have large metal hallways with red lights lining the roof or walls, it would be almost abandoned with pipes leaking toxic material and rusted areas everywhere
In every map there would be a small narrow cave that leads to somewhere random in the facility, that would be how to enter, it would also explain the reason why there are monsters in every map.
The map would be a wave map where once you kill all the monsters a new wave starts and spawns more monsters, sort of like the present.
Devs, you may add what ever more you want to this like a boss or how it looks.
modest dust