Wow, that was pretty awesome. It's quite hard to critize however, so I'm just gonna list a few good/bad things.
The graphics were really nice. I know it's just xkcd-style, but it looked very pretty. The mood and ambience was really good.
I loved the music as its own entity, but I did feel like it was just a bit out of place in the game.
The simplistic controls were very fitting (more complexity wouldn't have worked), buut it did feel just a tad too slow and linear. Also I think it would work better if the barrel moved by itself after the whirlpool, but that's just my opinion.
It's really cool that you made a "deep" and more meaningful game, when it's so easy to just make something funny or action-packed. I hope you do more of that :).
TLDR: Overall I really liked the game and can definitely recommend it (it only takes a couple minutes for gods sake!)