Well my first notice of the game is that it is not optimized , the game is so simple but it's size is large ( 200 MB) and it runs slow on my pc, the solution for this is simple it's just about textures and topology if models are made by you i think you will be able to fix this and make run soooo much smoother.
other than that the game looks are beautiful and i like the idea you used from the cold war and how you gamified it , good job man