is there anything in isaac you feel you could've done better, or anything you outright regret?

yes, i feel like the fact that you have to fight mom > moms heart > X final boss is a big flaw that was designed due to theme/story reasons.

i fix this a bit in the new game mode, but its something ill try to design around if/when we do isaac 2.

i also feel like other elements of isaac that could be more randomly generated, but i wont go into detail about what and how is fix it because again, its something id like to use in a sequel or totally new game.

and finally if i could id rebalance all items to the point where i could give the player more options in treasure rooms and boss rooms when it comes to items (ie spawing 2 items per area and getting to choose what one you want). but right now there will be an obvious power level choice between the 2.