Main model class was refactored and game-data storage was improved. Right now it's possible to record all the actions on the level and use it to undo any number of turns or to watch a replay (not available in the build yet).
Gif 1. Ability to undo any number of turns
You can try this feature as always in your desktop browser at craveforgames.com/...
There will be a post about the technology behind this feature soon.
UPD Feb 2016: LINK