Use arrow keys to move, and hold space to pick up the rock, and release to throw. You and the boss have 3-HP by the way. By the way, there is a timer which can be activated by pressing T. Click the green flag twice to fix some minor glitches.
Ok, so this may not be the best project because we only had 3 hours to do this, but I hope you enjoy it. I also worked with other people so give credit to these other nameless people who were in my group. By the way, I won :P This was in a contest.