Pretty cool!
But some thing's could be fixed, like the fact that units will get stuck on buildings.
Also, having to right click everything with the engineers gets a bit irritating so maybe adding a automatic option?
And of course, the progression is a bit fast, of course if that's your intention, it's fine, but it can get a tiny bit overwhelming.
Otherwise, great first game my mans! I know you probably will never see this, but please continue developing games!