There is no up here. The blocks drift at their own pace, and nobody can agree on where the floor is.
Tap a block and a small gravity field opens around it. The block gives up, falls, lands on the platform, and snaps into line with whatever is already there. Drop three and you have a three-high stack; drop them badly and the tower leans.
Zero gravity sounds romantic until you try to stack anything.
Zero gravity, floating blocks. Tap to drop them into one neat stack.