Carrion is fun. Old school 16 bit style fun where you play the monster.
RTCW is also old school, but that's because it actually is old.
Samurai Jack Battle Through Time is ridiculously, insanely hard. Like, the step up from Normal to Hard is a cliff face. It's insane. I cannot beat the second level boss. Wow. Just wow. Like hitting yourself in the face with a brick.