The movement and physics are both solid. I especially appreciated being able to jump mid-air after running off ledges. I really liked the character design for the player character; both their and the checkpoint flag's sprite look really good. The flip effect on the player character is very nice looking, too; its satisfying to spin back and forth in place.
The section in the first area where you have to make a series of jumps near the top of the screen was very awkward. You have very little room to jump before hitting your head on the ceiling.
I wish the reset key (R) wasn't right next to the interact key (E). I accidentally restarted the level a few times, which led to some frustration.
The checkpoints feel somewhat underutilized, perhaps because the game is fairly short. The "cross paths" theme also isn't very apparent.