Nice game, I like its idea. I think that this game will fit mobile devices the best.
I understand that it's just alpha, but, anyway, I'd like to put my thoughts about it.
Graphics. I'd highly recommend you to make higher-end graphics and change style from "low poly" to smth more pleasant for eye. I'm not against the "low poly" style, but when I see 10th+ game that uses this style, I'm like "Ohh, again..." If you have some folks who are good or who would like to train their skills in 3D modelling, you can ask them to help you; it's worth of it, because this game has potential.
Music and sounds. It just needs them both (:
Optimization. Despite the fact it has quite simple graphics, it runs too slow (I experience constant framedrops while playing it).
Gameplay. I guess you plan to add more complex puzzles with bigger maps. If so, then it would be good to have some zoom tool to zoom in and out to see whole the puzzle on the screen.
It would be great to have some level editor to allow people to create their own levels and share them with each other.
BTW, I don't see any economical part in this game (like "Stronghold" or "Knights and Merchants" have). For me it looks like just puzzle game.