I think it's a nicely thought of concept, fun to play. It can be expanded a lot with more variety (more zombies, traps, etc.). Also I get that it's more an action game than a TD game, but I think it would be better to manage difficulty by having a kind of resource to buy planks and strategically place them, than being able to hold right mouse button and just repair planks everywhere instantly (even so, it's difficult because the incremental difficulty of waves is high, I only reached wave 7).