Always like to see an FPS on a jam.
I found it a bit difficult to precisely aim falling cube, I'm able to rotate it so it get's bigger when it falls, but I can't really precisely land it to the red button, without going back and force. Could be cool, to draw a line from the center of a cube all the way down (and even up) so player can see where it's going to land.
Good job though, I know it's rather challenging to build a 3d fps game for a jam :)