Solid challenging little platformer, decent amount of variety in gameplay and clear graphics. The character feels pretty floaty in their jump, although I think that works in the game's favor because you really feel the pressure from the timer bearing down on you while you're waiting to land!
If you were looking to make adjustments to the jump, I think a variety in distance based on how long you hold down the jump key might be a good middle ground rather than increasing gravity overall, but the game works without it IMO.
The only other suggestion I might make is maybe some variety in music or maybe a longer track, it got a little repetitive by my 3rd death on the final stage.
Charming game!