Thank you for trying out our game!
Just to give insight on why things were the way they were at this time:
The parallax background was fine when I was testing it on the Unity Editor but I didn't notice that it would affect other players too much when it has been deployed. I'll make sure to check on it and reduce the speed so it will feel more in the background, but the behavior where it shifts depending on the player direction is intended so as to make it look like the player is going around the world and that the world is "huge".
Regarding the hidden enemies and spikes, the game was supposed to be for a 1920x1080 resolution but I encountered issues when uploading it here so I had to downscale it to 800x600, resulting in making it harder than it already is due to the smaller area of vision. There were also intended hidden enemies especially on the last level so it would feel like the "last, hardest level", but I guess it became too hard due to the resolution issue since even I took quite a time before I finished some of the levels after uploading.
The falling blocks having smaller hitbox than they look are intended so there could be a way for the player to "squeeze" themselves in some cases, but I didn't expect that the floor spikes would have a weird hitbox. I made them exactly as how the spikes look like so it's possible that it may be the player's, but I'll see what I can do with them to make them a bit more "friendlier" towards both experienced and new players alike.
Still, thank you for trying the game and for your feedback! I learned a lot and I'll make sure to keep it in mind. We're really glad that we were able to complete the game before the jam ended.