I'm normally turned off by long runs, but the Wind Waker run was a lot of fun. There was great energy between the runner, couch guys and announcer, there was enough variation in gameplay for it not to seem like a drag, and a ton of donations came in.
Probably won't stay up for Undertale (I don't want to see it run until I beat it myself), but I'm hoping the Super Metroid race gets tense.