Bluebird fly. Into the light of the dark black night
As usual, I am gonna be straightforward from the beginning - Grayland is a side-scroller, puzzle and adventure game, and I love it.
(Play in airplane mode so you don't have to see ugly ad blocks like this.)
The rule is simple: collect blue dots for energy, and avoid black spiky objects or cats or humans. The puzzles are not that complicated, but for someone who is not good at controls like me, they can be quite challenging (but not frustrating).