Shops sell various items in exchange for coins. Shops start at level 0 and only sell 2 items, but shops at higher levels sell more items. They can be upgraded through the Donation Machine, which can be commonly found in the shops and sometimes in an Arcade.
Shops also have a chance of being replaced by a miniboss room containing 贪婪 or 超级贪婪.
These rooms are locked and require one coin to be opened. Arcades can only spawn on even floors (Basement II, Caves II, Depths II, Utero II) or XL floors if the previous floor was completed with 5 or more coins. Arcades can contain Machines, Beggars, and other objects.
Challenge Rooms can only be entered if Isaac's total health (red, black, and soul hearts) is equal to or greater than his number of heart containers. Upon picking up its contents, Isaac has to fight three waves of enemies.
Boss Challenge Rooms can only be entered if Isaac has one or less red heart. Its contents are similar to the normal Challenge Room, but upon picking up its contents, Isaac has to fight two waves of Bosses instead of normal monsters.
Bedrooms require two bombs to open. Bedrooms contain a bed that can be used once to restore all of the player's health, or if they have no red hearts they give you 3 soul hearts and fully recharge their active item. Depending on if the bedroom is clean or dirty, bombing the center of the carpet will reveal a Crawl Space or a trapdoor leading to the next floor.
These rooms are entered through trapdoors with ladders in them. They can rarely be found under destroyed rocks. They can also be found using We Need To Go Deeper!, Ehwaz, or in a clean Bedroom. These rooms are viewed from the side, rather than the top like the rest of the rooms in the game. Crawl Spaces usually contain an item or various pickups. Rarely, the Crawl Space will lead to a Black Market.
Black Markets are accessed through Crawl Spaces. These rooms are 2 rooms wide and have 5 shop items that can all be bought for 1 heart container. Black Markets also contain a trapdoor to the next floor and various machines or beggars.
I AM ERROR rooms have a small chance of being reached upon teleporting. Every I AM ERROR room contains a trapdoor to the next floor along with various pickups or items. The only way out of an I AM ERROR room is through this trapdoor or by teleporting out.
If the player manages to beat 妈腿 in under 20 minutes (visually indicated by the clock icon that appears during the cutscene between floors), a crack will open in the wall of the boss room upon defeating her, allowing entry to a large room with 4 item pedestals in the center. Taking one of the four presented items will begin the Boss Rush.
This room is only found in the starting room of The Chest and The Dark Room. Opening this door requires Dad's Key or the two key pieces from Angels. Once the room is entered, Isaac will have to face off against the final boss, 超级撒旦.