The fact that it's free makes up for the fact that it looks free. You won't appreciate it for its art, and you won't enjoy the frame rate drops. Nonetheless, Dead Maze provides a fun, genuinely free-to-play experience.
Dead Maze, as a free-to-play and flash game, has a lot of issues. However, Atelier 801 gives us a social and funny experience that, with zombies and MMO, RPG and survival mechanics, can give hours and hours of joy.