The idea is supposed to be Icehouse
pieces (http://www.wunderland.com/icehouse/Default.html) on a
checkerboard; since the squares of the checkerboard are
1/4 the size of the LaserTank tiles, I explained it by saying in the
description that the pieces are larger than normal. Yes, I know some
of the arrangements of pieces resulting from the LTG are physically
impossible; I wasn't worried about that.
By the way, I have a suggestion for later versions of LaserTank:
allow the movable blocks to have a transparent background like the
other moving objects.