Quite ok for sokoban, but some deviation from the gameplay of the original would be nice. Something like different sized movable objects, or objects which could only be pushed vertically or horizontally. And puzzles get too hard too fast for my taste. For an example of a twist on sokoban style see Momors Mazemania Clik.Why would a flying saucer be pushing space ships into landing zones, something more evil would be fun.