I feel like the spawn rate of zombies can be adjusted, but otherwise solid. The isometric angle makes aiming a little awkward though, and not being able to see zombies at any other angle makes it easy for them to sneak up on the player. The controls were intuitive. Nothing much to say on visuals, but despite Unity making it decently easy to make something look nice with built-in lighting, physics, and assets (including models taken from your previous projects), there's a decent amount of polish which is very nice. My biggest UI/UX complaint would be the lack of an exit button though.