Cool idea with the moving walls. I thought the zombies didn't feel like a threat. I think it would be really fun to take this idea and make it into a multiplayer game, replacing the zombies with people.
A pretty smooth game. There seems to be something wrong with the rendering of the surrounding tiles. The player seems to slip under the tiles and blocks don't appear when I can collide with them. The audio is ok but I think the font is pretty hard to read.
The use of the theme is pretty nice, leads to good pacing. The controls are very nice to use.
The concept is good, even if spending a lot of time trapped inside walls can be a little annoying. But I had fun (and I liked the music)! Also, naming the player instead of taking the current time for the highscore board would be a plus.
Having the walls constantly shift around was a cool mechanic. It made the game more frantic as you run around shooting zombies and collection coins. The music did start to get pretty repetitive after a short amount of time.
It could us ea reload button. The relationship to the theme is tenuous at best.