This was fab, so fab infact that I have just remade this game, with new modes and chagable tilesets, get it here: http://www.caffeinekid.remakes.org/taketwo.htm
I agree with Pierre, this indeed is an addictive and fun game, even after a decade of 3d shoot-em-ups and other riff-raff this game still holds the standards of simplicity and playability.