dh_epic said:
Starting with multiplayer couldn't hurt. If you make it so MP doesn't degenerate into paratrooper wars, then maybe you can teach the AI how to deal.
This is a serious concern; spamming paratroopers could be a major problem. Ideally they would be less powerful than just about anything on the map; their job is to jump in and take out a resource, jump in and take out a supply line, jump in and interdict railroads, etc. Certainly WWII paratroopers were next to useless against a prepared enemy (witness the drops on Arnhem, Crete). When used mainly for interdiction (Normandy, Nimejen/Eindhoven), they were pretty successful.
I wouldn't worry about a paratroop promotion that would be given to a combat 3 or 4 veteren unit; pretty hard to spam those. I'd suggest that the paratroop promotion also come with some additional benefits; perhaps +10% base strength like a combat promotion, or something: after all, most paratroop units have traditionally been used as elite infantry. Units that start with paratrooper should be weaker, like Str 16 + free paratroop for base str of 17.6; weaker than infantry, but still useful. Might be nice to have paramobile artillery, too, perhaps like the poison gas (str 6) in the WWI mod; essentially only good for bombarding or as throw-away units.
Might be nice to have an air transport unit that needed to be in the same square as the paratrooper with a movement point; paradropping would use up the movement point of the paratrooper and the air transport; I think that might be possible in python. That would solve the basing problem (can only paradrop from somewhere with an air base), you could allow interception of the air transport unit, which would allow fighter interdiction of the paradrop, and you'd need to commit a few more resources to the drop, which would help prevent spamming.