Young Isaac lives peacefully with his mother, until of course the heavenly voice of God demands she sacrifices him to prove her loyalty. Isaac escapes via a trap door in his bedroom into a disturbing basement full of freakish creatures, lost siblings and slot machines.
The Binding of Isaac has gameplay with a very heavy nod to The Legend of Zelda, complete with a heart meter and secret areas uncovered by bombs. The bosses, while freakish in nature, often resemble those from the Zelda series, though the game puts an interesting spin on the concept with randomly generated maps and power-ups.
The game is unrelenting -- if you die you must begin the entire game again. There is no ability to save, thus you have to make every move count. Upon starting again, the random map feature kicks in with a whole new set of rooms and power-ups for the subsequent playthrough. Isaac's primary weapon is to fire his tears at enemies. These can be upgraded with chocolate milk and other items. He also imagines one of his worst fears each time he ventures deeper into the basement... with a depressing reminder of his unhappy childhood the only way to celebrate getting that one level further.
On the 29th of May an expansion was released, containing over 100 new items, 5 new chapters as well as a number of new enemies, achievements, music and more.