Arrow keys to move the ball and use the mouse to pick up the cube and bring it to other places. The button opens the door and you can walk through an open door to get to the next level.
Big thanks to @-Amazerro for helping me out with this! This was an idea from awhile back, I'm really glad I was able to make this happen. Story: You play as a ball that has been trapped in a colorless laboratory to be tested and re-tested over and over again for eternity. You have to escape!