The Binding of Isaac: Rebirth is a remake/expansion/special edition version of the cult hit roguelike/twin stick shooter/zelda clone/child abuse simulator The Binding of Isaac, which came out a little over three years go. It's a game that mixes religious iconography with old Newgrounds memes, stories of abuse with poop jokes, and the nightmares of a broken child with whimsical videogame tropes. Kind of an odd duck, really, and a whole lot of fun.
The original was something of a Let's Play sensation, with one guy named Northernlion making a nearly 1000 part Let's Play. (If you count his videos of the community remix mod, he's broken that 1000 mark.) The game's success was almost entirely due to word of mouth.
Now, you may be asking, if the first one is only three years old, and is fun enough for people to still be playing it, why is a remake happening? Well, because its creators didn't expect the game to get as big as it did and made the thing in Flash, expecting it to take maybe a week to make and then they could sell it to Adult Swim. The thing is, the game is broken in ways they simply can't fix and they can't add any more content to it than they already have with the game's one major DLC pack, The Wrath Of The Lamb. Developer Nicalis (who've done, among other things, the for-pay version of Cave Story) approached Edmund McMillen with an offer to make a bigger, better version of the game to port to consoles, and the rest is history.
(this trailer is super NSFW, fyi)
TBOI:R drops on Steam, PS4, and PSVita on November 4th, 2014, and possibly to other things in the future, who knows.
edit:
Here's a good new wiki for stuff, including a number of special seed codes (maybe something for the op?): http://bindingofisaacrebirth.gamepedia.com/Binding_of_Isaac:_Rebirth_Wiki