Pretty neat game you have here. I played the game twice, one to try out the game and the second time to analyze and break it down.
No music on the title screen confused me and I thought I muted my speakers xd.
No sound switching between menu options, only sound when going into the instruction screen.
Covers jumping and other things in the menu, but not movement.
Character sprites overlap wall sprites slightly and box sprite
Sound effects on touching the post/ reaching the portal and restarting the game, none for movement or jumping
You introduce the balance beam on level two but not incorporating it into the level to finish it
In level three you do use it but it feels strange to me, it could be the pacing of the mechanic of which you were going for, but it just feels weird to introduce the mechanic but not use it, but rather to test it out
The balance beams sometimes remove my jumping input, but you did note them as glitchable but still works well, so kudos to that.
Mechanic pacing is alittle off to me, I played with only the balance beams for 7 levels then got introduce to the Boxes for ONE level, then gotten introduced to the last mechanic the destroying floors on the next level... You introduced something new to me, rather than using the levels to expand on the new mechanic with existing mechanic(s) you showed me. Which you do throughout 10-14 then bring it all together on 15.
This one is more of a reflex, but everytime time I die, I go towards R to restart the game, but that brings up the menu and a few times I had my progress restarted from pressing R into X.
Overall it's a great game and I'm looking forward to your next creation! :)