It is similar, but I put a different twist on it, mainly the fact that they Always move together, and the fact that it used a hexagonal grid instead of a square one, which actually made a really interesting mechanic! and I had a couple of puzzles there that we really cool!
Its not too long, so it wont really take long (about 20 levels if you include tutorials and ending levels)I've got a lot of reviews there so don't feel obligated to try it out, but if you want its just as free as all of my other games! :)