MadWorld
I don't know if the game actually got more challenging, or if I'm just taking a different approach - but I actually had a lot of fun with level 2. The boss fight, too, was very cool, although I'm not sure if I did it right. Level 3 provided a good break from the action in the form of motorcycle-riding mayhem, followed by an on-foot boss encounter that really threw me for a loop, but I was able to get through it with an extra life.
In level 4, I didn't realize until about 15-20 minutes in that I was supposed to climb the walls of buildings to get inside. And then at the boss, I didn't figure out (or rather, see) the right strategy until I was already approaching a game over. When it challenges you, the game is definitely fun, but the black and white aesthetic does detract from it, for lack of visual assistance in figuring the game out. I'll just have to look harder, I guess.
Unfortunately, game voice-overs are only fun so long as they don't broken-record themselves, and that's what the announcers started to do as early as level 2. It got almost unbearable in level 3, when they kept spouting the same "Jack can't ride ride a motorcycle" quip every 30 seconds. Hearing new stuff from them is hilarious, but I wish they wouldn't repeat themselves so much.
Progress: Level 4: Great Wall Street