I don't have a numpad... it would have been nice if you had provided an alternative layout like
QWE
ASD
ZXC
for people without a numpad, or you could make it so you can click/tap the squares.
Yes, I thought about notebook users, I'm going to add another Input schemes, or even the mouse, as suggested.
Game updated. Now you can play using the Q W E A S D Z X C control scheme.