I gave up on 4. Honestly, It's more annoying than fun. I'd prefer that instead of the 2 dying when they touch eachother they just stacked.
Very good idea for a puzzle and it's fun.
Cool game, nice concept. BUT as the game gets tricky, we need a faster "restart", why I have to press "Space " to begin? It pisses me off! lol make it more dynamic and let me just press "R" and begin playing.
You can restart the level pressing "R" in the keyboard or with the mouse in the interface. Also for star you also can click the left-mouse button or any key