When you press green flag, a gray block will start falling. Your objective is to push the block back to top with your mouse to advance to next level. Complete as many levels as you can in time. But be careful, because you have limited lives as well. Complete levels with only few moves to get more points. Enjoy Coming soon. DNLTBFD Speed (a faster version of this game)
Thanks to my classmate for the original game. Both versions can also be played on whiteboard (and maybe even blackboard).