A perma death roguelike -with some permeant upgrades and a perk system -- think hades. This is basically skeletal avenger
1) A Randomized multifloor dungeon with boss at the end.
2) Upgrade system to keep the player hooked into the game
3) You gain crystals when you defeat a boss, you lose crystals when you die. All perks are lost when you die.
4) It costs crystals to try to beat the more complex dungeons. If you run out of crystals you will have to go back to the low level system.