Glad you enjoyed it :)
Yeah trees are a bit weird one. I did them fairly early on and ended up tweaking all other things and left trees as not that important to gameplay.
It moves 2px at the same time blocks move 1px. At some point I had it so it moves 1px half the waiting time, but it started flickering with dither, so this seemed like more graceful way of doing it.
The colours and foreground/background are clashing a little bit too, so I agree, there's definitely room for more polish :)
Again, thank you for playing!