Hard mode is a mode added to The Binding of Isaac: Rebirth and also the Eternal Edition DLC for the original game. It changes the gameplay in certain ways to make it harder. When playing in hard mode, a little red pentagram appears on the HUD, below the consumables.
- Rooms contain more advanced enemies and in a higher number.
- Causes champions to spawn more often, however, they award less consumables.
- You are less likely to receive a Pickup after completing a room.
- Bosses no longer drop red hearts when defeating them.
- You are more likely to be cursed on each floor.
- You are more likely to receive the harder version of a floor (e.g. Necropolis instead of The Depths)
- Using the Dice more than once on an item may cause it to disappear as if it was picked up (Vanilla only)
- Guppy's Paw only grants 2 soul hearts instead of 3 (Vanilla only)
- You are more likely to drop Eternal hearts.
Completing Hard Mode will put a red aura over the completion marks on the character selection screen for the character beaten with.