There are eleven playable characters in The Binding of Isaac: Rebirth with three extra characters in the DLCs. Five of these characters (Isaac, Magdalene, Cain, Judas, and ???/Blue Baby) came with the original Binding of Isaac, while two additional characters (Eve and Samson) were added later.
Azazel is a new character in The Binding of Isaac: Rebirth unlocked by making three deals with the devil in one run. Azazel starts with a short-ranged version of Brimstone , the ability to fly, the card 0 - The Fool , and three black hearts without any regular heart containers; however, unlike...
Seeds, essentially random strings of characters, are used as the basis for all decision making in the game. By inputting a seed manually, you can guarantee that most randomly-generated decisions will occur the same every time.
The Binding of Isaac: Rebirth (commonly referred to as Rebirth for short) is the remake of the original Flash game The Binding of Isaac. It was developed by Nicalis with Edmund McMillen in a supervising position.