Fun game, though very slow paced.
Would have been more interesting if the enemies could use tanks/airstrikes. I feel like the machine gunner might be a bit too strong, since one machine gunner can pretty much take on an infinite supply of normal soldiers (and that's all they generally throw at you).
Would have been nice to have some simple effects for when the machine gunner, sniper, and tank are shooting so you can gauge how effective they are.