It's minimal and I think still qualifies as low-effort, but a fully functional game. The length is about right, but I wasn't expecting the difficulty ramp to come as late as it did. The basic zombies are actually the scarier ones, because they move fast, the field is tiny, and hits don't stun or knockback at all. I found avoiding the boss bullets to be pretty much impossible, but you have a deep enough health pool that it doesn't matter that much.