One heck of an ambitious game to pull off in 3 hours, well done!
On a design note, after just a couple of speed upgrades, the camera was having a hard time keeping up with my character. Similarly, I jumped off of a tall platform and it took about 15 seconds to join me again down on the ground, so I would personally recommend reworking the camera sensitivity when you make a similar game in the future!
As a quick bug report, I discovered I was able to fly, as there was no limit on how many times I could jump!