Few ideas, some of them I presented also in my concept:
1. only one basic infantry unit - conscripts (4men) which then through upgrades will become other type - specialization:
- stormpioneers, flamers upgrade, building unit, MP40
- grenadiers, basic inf better than conscripts
- stormtroopers, elite inf, can move thgrough water in rubber boats, can assault garrisoned buildings
- MG infantry, MG42
- Mortar inf, 8cm mortar
- AT gun, 3.7cm Pak, upgrade to 5cm Pak or later to 7.5cm Pak
- INF gun 7.5cm IG18 or later to 10.5cm GebH40
- 2 snipers units
- logistic squad (or supply squad) - infantry unit which will increase the resources flow from sector
2. same could be applied to 1 basic halftrack unit Sdkfz 251 (maybe on tanks too), normal troop carrier with upgrades:
- command HT (acts as vet.sergeant reducing suppression and increasing exp.of infantry)
- INF gun
- AT gun
- Flak 38
- Flamer
- Mortar
- MG42 platform
- recon HT (can see other troops on minimap, like PE Vampire, can cloak)
3. global experience, the point is that all units experience gained is counted together in one building and then redistributed to individual units as medals, giving this unit some benefits.
4. economy war (as doctrine) - special doctrine for players who want to play indirectly and boosting own/ hurting enemy economy, resource income, production time, pop.cap etc.
5. quick deploy - tanks could be deployed with half of original cost in fuel (like PzIV 80fuel will cost only 40fuel) but will decrease permanently fuel income by 2fuel/min. f.e., this deploy would be possible only until minimum fuel income
6. fronts shifting - units could be sent to help on other fronts and then could be retrieved back after some time (10min.) with some benefits - newer model, more units will come back, veterans will come back etc., it would be like investing units, small sacrifice in begin with bigger benefit later
7. smoke mines - pioneers can build smoke mines with no damage effect only creating covering smoke when enemy steps on it, blinding him for a while, could be less expensive than normal mines 5ammo f.e.
