Isaac is a roguelike shooter based on the dungeon structure of Zelda (nes). At its core it controls like Smash TV / Robotron in a randomly generated semi RPG world filled with powerups items and special abilities.
There is not a traditional leveling system in Isaac, instead we used an item system. Every level will have a treasure room, shop, boss and other secret/special rooms that might contain unique items. Special items come in 4 sets, Usable items, Special Weapon upgrades, Passive upgrades and stat boosters. 90% of items in the game stack, so as you progress your character will change into a monstrous powerhouse not only in stats and abilities but also in appearance.