TNT Evilution: it was fine, albeit a bit too easy? Lots of levels that feel like they're just too big for the number of enemies they contain.

The Plutonia Experiment: hilariously hard, and I don't particularly enjoy playing it. That being said, the reason for its difficulty stems from a thorough understanding of how to use a lot of the enemies effectively. like with the Archviles resurrecting the seemingly infinite number of chaingunners to ruin your day. I have to respect that.