In the world of free truck games there are many choices but the correct one is: Rusty Racer. You don't only get to drive a truck but you also have to make stunts. In the first level of this free truck game you need to make 2 flips in order to continue. It's hard to rotate the monster truck twice during one jump so it's recommended to take your time.
The controls are easy to use. The up key is the acceleration, down is for braking and left/right to tilt the truck. If your vehicle is upside down on the ground, you can accelerate no more so you have to tilt the truck while pressing up. The best way to get back on your wheels is to hold up and the left arrow keys and the truck will be working in no time.
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To perform a back-flip you need to hold left before the jump starts and after you completed a full 360, try to find your balance. If the truck crashes before the complete 360 you don't get any credit for that. In real life if you don't land on the wheels, you are not a monster truck driver any more.
The best thing about these free truck games is that you don't have to download them and you don't need to pay anything. Forget the credit cards and the complicated installation kits. This is an free game so enjoy it!