Nice idea with simple mechanic. Definitely can be develop further. 

For me player feels too slippery. Adding more friction would help with precise movement that this game demands.

Keep it up!

Not a bad little puzzler, my main suggestion is to actually show or type SPACEBAR instead of up in the beginning because I kept pressing up and I thought my game was bugged. Also, showing R right after and making me restart was cruel lol. Put the controls in the beginning  instead for a more smooth gameplay loop! Overall you're onto something here, felt like an old newgrounds puzzler!

Hmm... maybe a slower ramp up on the difficulty. I was having trouble at the first spikes. I did like what little i got to see though

This is neat. The space bar seems to repeat to quickly or something. I feel like I was regularly flipping gravity twice when I meant to only do it once.

I don't think any other game I play this jam can reach the amount of pain I felt when I almost completed the tutorial only to get stuck on a wall mid invert and die. 10/10 would try to beat testicle-shaterringly difficult tutorial again.

Agree with the previous comment, the learning curve can be more newbie friendly.

And other than timing the jump, maybe putting puzzle solving would be more attractive.

Also, it might be a good idea to add save points T_T

Very good idea but eeven the tutorial is pretty difficult.