Cool game! Absolutely love the way the tank and billboard sprites look. Can really imagine a non-game jam version of this with a billion zombies and a bit more momentum on the driving physics, particularly when Nitro is activated. Also I wonder if its worth making the player stop or slow down to get upgrades? Perhaps this would work a bit better if there was a ton of zombies coming at you that were a serious threat or something? Anyway, lots of potential in this one, great work!!