Game File: 

christmas-pk.zip

Use the arrow keys to move the floor left and right. If a block lands where the floor is a different colour to itself, something bad happens depending on the mode; otherwise, it stays where it lands. Press space to release all landed blocks and gain points; the more blocks on the ground, the more points you get. Easy mode does not have a lose condition.

left/right, A/D: move.
space, up, W: release blocks on the ground.
1, 2: select a mode on the title screen.
1, 2, enter, space: continue at the lose screen.
escape, backspace: quit to title; exit at title.

W/A/D works for other keyboard layouts too: QWERTZ, AZERTY, Dvorak, Colemak.