It's nice, but I don't like the green stage.

Im Liking this game to be honest nice work :D

The game feels, how do I put this, unfair? Non-descriptive? I don't know, probably both. It has some potential, but the physics really throw me off. It oddly enough reminds me of Meat Boy, the old school one, not Super Meat Boy, with it being so floaty. At first I thought, "Wow, this game is super floaty, (which I like) yet it can't take advantage of that because the jump is so short." Then I discovered the fact that there's a double jump. And that was a while into the game, too. The player needs to know that, "Hey, you can jump on those white platforms, but don't touch the red, or you'll die. Press up twice to Double Jump," or even the fact that you can stomp on enemies instead of having to avoid them is super important. If you don't communicate to the player what they can do, they'll just end up stuck and confused, and in most cases, think the game is broken.
There was also a couple issues with the level design that made it feel unfair. Like those portals. That very first portal was very poorly placed, since when you jump into it from the bottom, you're upwards momentum from your jump carries you right into the spikes on top. In order to safely get to the other side of the portal, you have to do some very clunky-feeling platforming. If that's just a troll, you should convey that it's a troll rather than some bad game design.
I also got really lost in the levels, because there's just so much going on onscreen at once. I felt like I could make it to a lot of the platforms that I just couldn't, and the level design overall is very poor. I also didn't know what the white outlined boxes do because, again, it wasn't conveyed properly what they do. Then at one point, I hit it on accident and it had those white, thunderbolt-looking appendages come out of it like at the start of the level. Then is when I realized that it was a checkpoint, and that I'd been wrong in thinking that the game was kind of like a Geometry Dash level where you need to have the muscle memory to be able to complete an ultra-difficult 2 minute level.
So what can you do to help combat these things? Well, I know that you just started game development, (due to the author comments stating that) so I'll give you some tips. First and foremost, play testing. Personally, I have some people that I can contact to help me review my games in their early stages through my Email, for you it could be friends, family, or giving it to some gaming forum. Then I can get help with knowing what I did wrong in my game, like something being not conveyed properly or well. Another tip I can give you is to have a difficulty curve. Start out with something really basic and tutorial-like to give the player a feel for how the game works before they get thrust into more difficult levels. Your game also needs to have fleshed out levels. Even just having occasional arrows and warning signs that are purely cosmetic could help out, or stretching out a level horizontally as apposed to more vertically could convey just where the player needs to go. One last thing is that players enjoy instant gratification as opposed to a long grind. The 4 levels in this game are justified because they're so long, however, if you were to make say 20 levels that are shorter but apply the same concepts as what you have in these four levels, the experience will be a lot less frustrating, and a lot more rewarding.
Though you are getting a lot of stuff right, too.

For example, you're (so far) very good at creating an atmosphere. The grungy, Tron-esque yet cartoony art-style is suprisingly good, though it might need some touch-ups. You also hardly have any bugs to speak of. The only thing I could find was that I was able to stand on an enemy right at the corner of it's hitbox without getting killed nor killing it. 4 years of game development (almost 5) and I haven't been able to cinch out the bugs to just 1 in the base game without some patches.

Overall, a pretty decent start to game development, however with a few surprisingly glaring issues that hinder the gameplay a lot. Sorry for the harsh wording at the start, but keep up the good work. Also, PS, haven't finished the game really, so correct anything I said wrong.

Challenging enough that checkpoints should be closer together.

Definitely needs a Tutorial and a bit of map adjustment, besides that it's really good!