Thanks a lot for the detailed feedback Lanyard !
You're right, the core of the gameplay (go up until you hit something by the bottom then reverse) is not as obvious as I thought it was, other playtesters had the same complain (I played a lot of similar games so I underestimated the subtility of the concept). I'll try to include more visual clues to convey the idea that UP/DOWN is not the same as LEFT/RIGHT.
And right again for the "puzzle or action" part. A vague idea I have is to allow the speed to be altered at runtime (you can in Frozen Fruit, another Crillion-like I enjoyed a lot), so you may either go full speed to set a highscore, or slow to solve the puzzle.
Thanks for playing and setting highscore <3 !