In my experience, the only two units you need for gold medal on any level other than bunker levels are the spy and the heli-g. the heli-g can snipe enemies and kill without explosions while the spy can move through areas with few enemies and rescue vips/civilians. don't try to move too quickly and keep building damage to a minimum. the spy bomb can kill enemies if you drop it at the edge of their field of vision (it should just barely be in the red).
One of the few games I've played that is literally laugh out loud funny. I applaud the effort of everyone involved and I can't wait for Upgrade Complete 3.
I feel like the points mode, while hard, is kind of lazily programmed. "We need to make it harder. What should we do?" More blues. "But there's already fifty on screen!" Damnit, I said more blues.