Yeah this game needs some polish. The song loop is good as is but the towers need to be balanced a little. Or a lot. Emma seems kinda useless, the basic soldier seems less useless up until past the 10th wave where they only manage a couple of pity kills, niko seems pretty good and Jack seems like the one you're just supposed to buy and upgrade instead of getting any others.
The zombies also just get tougher without any visual change? After the buff ones and the lightning ones there's no bigger badder ones but they sure as hell take more bullets. The dog at least gets tougher, but spamming him nonstop every 5 seconds seems more like a bandaid on design then something helpful.
So yeah all in all it feels "playable" but a perfect run seems like something you got to meticulously plan instead of something you can get provided some effort and a few solid tries.