It seems that people usually need to play once or a few times before getting a good grasp of game mechanics (Sorry for not making any tutorial). However the game is beatable on hardest settings - Axetreme difficulty and small map. I've just posted a video showing how it can be achieved. I also decided not to use the spot on the bottom right corner of the map to make it even harder - that is the only place with one exit/entry. Link to the video is on the game page.