Gameplay wise it is a good game for quick play, camera and controls are easy to understand and easy to use. Nice game made really fast
Few things I spotted: its little annoying that the tree trunks are blocking the way, I guess destroying them would be not only nice, but it wouldnt be that annoying. Jeeps sometimes pop up on screen. If you want to make count down to restart the game, it will be better if the time will count down not up. Explosions should be damaging enemies too, it looks unfair that small jeep survive near miss with that huge explosion, miss explosion might be smaller than hit explosion. Muzzle flashes might be little smaller, it looks too noisy. Game map is very little IMO. It took me awhile, when I realized that you have the control of how far you shoot, Cross with line for indicating the range and position where the hit will land would be good (and maybe explosion radius).
Graphically the game looks good, I like explosion effects, overall the game has its style. I would use some old army like font instead IMO it doesnt fit to the visual style. Little spread to bullets would look good, trees with swaying effect might be parallaxed that would look cool, shadow is static, might be dynamic (kind of). Ricochet effect, might be good idea for indicating damage. Making color dynamic health would help distinguish how many HP you have. Sounds are minimalistic but cool
btw you can try my game I released yesterday too
Keep it up, hope it helps!