The Binding of Isaac creator Edmund McMillen said April's Forgotten update for The Binding of Isaac: Afterbirth+, a collection of add-ons for The Binding of Isaac: Rebirth, would be the game's final free booster pack. However, earlier this year McMillen told Polygon that he's "never done" with Isaac, and according to publisher Nicalis, there's more Isaac in store—in addition to the Four Souls card game, that is. The publisher tweeted a brief teaser for a new game (or add-on) titled The Binding of Isaac: Repentance last night.

Some players have pointed out that the logo for Repentance bears a strong resemblance to The Binding of Isaac: Antibirth, a free fan-made expansion released in December 2016. At the time, McMillen discussed officially adding the mod to Afterbirth+, and when we spoke with him about the influence mods had on Isaac's popularity, he described Antibirth creator The-Vinh Truong as being "on a whole other level" from other modders. So it's possible Repentance will integrate Antibirth or other mods in some way, but take that as the speculation that it is, since neither Nicarlis nor McMillen have confirmed anything.

For his part, McMillen offered a tease of his own on Twitter around the time the trailer went live.

The Binding of Isaac: Repentance will be at PAX West, and so will we, so sit tight for more information.