Because this is logic game it could have a undo button that makes one step back. Just like puzzle script puzzles. Also level selector could be good in this demo.
P.S.
Oh. Figure out that checkpoints are probably a part of puzzle. But anyway undo step would still work like in puzzle-script games. Just including take of checkpoint scrolls.
P.P.S
There is a bug with spikes. When they half go away, if to move on them too fast they kill. Not good.
P.P.P.S
On the level 24 spikes even got desynchronized. One row of spikes started to in/out on different step than everything else