My favorite part about this game is the music, which isn't in the "favorite aspect" selection for some reason. The first few levels seemed to teach you about different parts of the game. The first one taught you the basic controls, the second one taught you about midair jumping, and the third one is where the difficulty goes up to make you good at the game.

The graphics definitely need some work. The excessive amount of gradients was kind of hard to look at.

If you're doing a platformer like this, I recommend working on the controls to make them more use friendly. For example, in a lot of well made platformers, if you jump a little bit before you hit the ground, you'll jump as soon as you hit the ground. The whole jumping higher when you hold down space thing felt a bit weird. I'm not very experienced with that mechanic, so I'm not too sure why.

The difficulty of this game is also an issue. There's a pretty big difference between hard(which can be good) and punishing. This game feels punishing because a slight mistake can cause you to die(which isn't always bad) and because the levels are so drawn out. If the levels were a bit shorter, this type of difficulty would work a bit better. As was previously suggested, I'd recommend using checkpoints at some point in a level. Maybe not every triangle, but there definitely needs to be some.