Earlier this year The Binding of Isaac programmer Florian Himsl said he would add more difficult "eternal" versions of bosses to the original game. As it turns out, he went one step further and added an entire optional hard mode in an update that recently went live to those who own the Wrath of the Lamb DLC on PC.
The Mac version update will follow next week, Himsl noted.
According to The Binding of Isaac developer Edmund McMillen on his blog, Himsl's goal was "to make the most challenging and trolly version of Isaac ever... and I think he succeeded in doing so."
"Now I wont say I think this mode is the most balanced thing in the world, because it is not, even in the slightest, but as an optional mode for an old game I thought, what the hell. I'm sure there are more than enough sadists out there who like to be toyed with."
"Honestly though, there are more than a few additions Florian added that I think are quite interesting," he added. "And even though the hard mode isn't for everyone, I think any Isaac fan will get a kick out of just how randomly ridiculous some of the new additions are."
Here's how the new Eternal bosses look in action:
Regarding The Binding of Isaac Rebirth's upcoming Afterbirth DLC, McMillen noted that it will add alternate versions of the game's various subterranean floors. While most floors already have "alt chapters", McMillen figured that rather than add a third potential alternative to Basement or Cellar, he'd add new filters like make the existing levels on fire.
The Burning Basement/Cellar will feature more flaming versions of foes and fire pits will replace certain rock formations. This will make the Burning alt versions of the levels harder - sort of like the random dark levels in Spelunky - but they'll also feature greater rewards. "These seem like minor changes but in a lot of ways these new alt levels will act as 'champion' variations of levels, making things slightly harder but also raising the possibility of more reward."
Finally, McMillen said he'd like to alter the stats for the game's incredibly secretive character The Lost. Designed to be a meta puzzle for the community to solve, unlocking The Lost is an abnormally convoluted process, but diehard fans have done it anyway. This Rebirth-exclusive character is a ghost who starts the game with no health and can't pick up any, so one hit and it's lights out. On the plus side, The Lost can fly.
That was all well and good, but McMillen felt that this character was underpowered, even as a secretive challenge. "I think The Lost is probably the most exciting aspect of the game," the developer said. "I've been playing as him for the last week and having more fun with the game than I ever have before... The Lost totally changes the game and makes you rethink every items power level... And that's just good game design."
"Sadly not every aspect of The Lost reflects this," he lamented. As such, he's pondering whether he should make this character's movement quicker, give it Spectral Tears that can shoot through obstacles, or both. McMillen is asking the community to vote about it on Reddit.