Playable on mobile too!

THE GOAL — sort the tiles 1 through 8. Though it might spell CAT ATE TEN.

THE CONTROLS 

— Move : WASD, arrow keys, click.

— Confirm : Space, click

— Restar : R

It's a sliding 8-puzzle. You decide how long you should need to solve it — then try to actually do it in that time.

But padding your timer to play it safe? That'll come back to haunt you.