[Fictional story]
After the Soviet occupation of the western part (where the Bandit Airport is located) of Krakabloa Islands in the 1960s, the Bandit part has taken into possession a solid amount of Soviet-produced trucks. Due to the lack of anti-aircraft tanks, the separatist group named "Krakobloan Democratic Republic" has converted the trucks into flatbeds, and mounted 25mm anti-aircraft guns on the chassis. The air defence trucks are reliable, have good offroad capabilities and comfortable controls.
To drive this vehicle, use Pitch and Roll. The gun mount is automatically aiming.
Now, speaking of the details of the gun itself: it is a high-damage machine gun with a 15-round magazine (reloading takes 5 seconds). Has a bit slower than average firing speed, but one hit makes 60 damage, and the accuracy is high. Also, I put a piston in the cannon, so there are some recoil visual effects.

Important note: the vehicle is not mine, all I did was add a flatbed chassis and my gun.
Please enjoy, feel free to comment anything you fancy.