Strange, but I was unable to walk. Not WASD not arrows respond. Strange. Anyway, enjoyable shooting and interesting concept. Good idea that zombies immune when swim. Wished there be more elements to build or variation of enemies.
It is possible to destroy the tile/plank you are standing on, but you can rebuild the planks to regain movement. If that doesn't solve the issue then there might be a bug I am unaware of.
