This is extremely clever. Well done!

Your friend needs to explain what the goal of this game is up front! As soon as I saw the video I got the mechanic immediately--but had no idea what sort of scoring system was involved. Normal tetris scoring doesn't seem to apply, because you can't clear lines. It looks to me like this is a co-op game, which was not immediately clear. If I'm correct, you want to last as many bricks/as long a time as possible.

You need to state very clearly that it's co-op and the goal is to stay alive for as many blocks as possible.