I, for one think it would be pretty cool if the HOI series made a move away from 2d maps to full 3d maps (which would provide more tactical situations, etc). What about you?
1. 3D maps, that can be rotated, tilted and zoomed. Use googleearth if you have too.
2. Light tanks evolve into mediums and cease being a buildable item at some point. Mediums evolve into MBTs. Or in the case of USSR, the JS-3 becomes the T54. Work it out. None of the HOI family of games has been satisfactory in this regard.
3. Inf can be upgraded to motorized or mech. Cav can be upgraded to Inf, Armor, motorized or mech. My dad enlisted in the Horse Cavalry in 1939, his Cav division ended up the 6th Armored Division.
4. Corps artillery. Organic corps artillery.
5. No provinces. Dynamic front lines.
6. Reduce Strategic Air to its historic effect. Near none. Germany's economy was growing right up to the end of the war. Germany's benzene production also grew, right up to the end of the war.
7. There needs to be a re-balancing of Units. A T-26 division (or division of Matilda and Cruiser Tanks, for that matter) in no way equals a Pzkw III/IV division (this has a little to do with land doctrine and nearly everything to do with Quality and Design). Some divisions should be more "powerful" than some corps.
8. And similarly, some way should be found to model the historic differences in strength of the various Great Power's division size units. Not all divisions were created equal. Again, no member of the HOI family has been successful with this.
9. TAC, CAS and INT/FIGHTER are nice to have, in a tactical level game. I'm not sure it wouldn't be better just to simulate these in the background based upon a percentage of IC.
10. Supply Trains. Whether they be 20 mule teams, the Red Ball Express or the Berlin Airlift, I don't care.
11. Bridges and Bridging. All major rivers must be bridged. Bridges must be held. Bridges can be targeted for bombings and destroyed. Men and material (supplies) stop crossing when the bridge(s) is destroyed. Just because you hold both sides of the Rhine doesn't mean you can get significant supplies and personnel across.
12. Landing craft (amtracs, LCP, LST, LCA and the like) Just having marines ain't enough. Especially since most landings by the American military was done by the Army, not the Marines. These items evolved during the war . . . just like armor and everything else. The Pacific theater has been neglected.
13. Afrika Korp