I always loved I Wanna Be The Guy back then, and while I did not beat it back then, I always wanted to beat it and so I did. Enjoyed it a lot, and then after further playing around with it, especially with boss rush mode, I thought, maybe Impossible mode is not so bad. Boy was I wrong lol. Still was fairly fun to learn and do, and didn't take too too long but still, it's quite a challenge.
Time: ~15h