Nice and tricky game, I got stuck on lvl 17 for a good 20 minutes until I figured out I could use this red no-gravity field to keep multiple boxes suspended in the air.
Everything beyond that I figured out much quicker, even got all medals.
I personally did it on lvl 8, but it might be possible on other levels too, don't wanna check them all though. A laser has to be aimed horizontally onto a camera for a few seconds, it doesnt work vertically.
Simply do nothing, shield yourself, or shield both you and the other guy for the 3 endings
I also read in the comments that the game is a "cheap copy" of portal in some manner. Guess they never heard of tributes. You did a good job with that game, I liked it!