I made it to level 121...how much farther does this go?!
(I'm guessing it's endless and procedurally generated.)
Well, anyway, this is definitely fitting the bill, i.e. being a game that can be idled but also doesn't running for weeks. Being able to get to what's functionally the end of the game in half a day made it actually rather reasonable as far as idle games go.
I read that the browser saves my progress. I hope it does since it's taken half a day to get here, and I'm gonna have to stop until maybe the next update or something.
Edit: oof, I had an all-tree spawn on 121 but still didn't beat it. aww...
Edit: beat 121, finally!