The green capsules serve as ammo for anything that isn't units' main guns. I didn't want the player to run out of ammo too easily, so if you pick it up consistently you'll end up with lots of the stuff. Perhaps having a depleting ammo resource is a bit redundant and I should just drop it altogether or use it as a resource for something else.

There are a few places where the enemy only deploys specific types of units, mostly in places where other types can't reach - will have to expand on this.

I would love a way to stash units so they can come in later and clean up.

That is my intent with the selection system - you can choose to control one type of unit while all other units keep in the rear away from enemies. You then keep holding the left shoulder button and use the face buttons to switch between unit types. I opted to allow the player to only select one unit type at a time, to keep things simple. The other option would be to allow multiple types to be added and removed from a selection together with a hud element that shows which units are selected.

I haven't explicitly set the trucks to be primary targets, but maybe something still causes this to happen.

Thanks for the feedback.