The Federalist said:One version or setup to be played ONLY as Axis.
One version or setup to be played ONLY as Allies.
If you want that, you should go for the "Stony Road" Mod. Last time I checked it had exactly these tailored versions and I didn't like it because it was totally loopsided, ahistorical and did "landing by event" in provinces without a beach. On the other hand I like HARD CORE (except for the "Sabotage Research" events :-( because it still feels somehow historical.
But to the question on increasing difficulty. I'm not sure if further strengthening the AIs by allowing cheaper production/research is the right direction. This is exactly the way Stony Road went (and which now can seemingly also happen in HARD CORE with the USSR fielding 100s of ready, teched-up divisions before Barbarossa). This is just covering the weaknesses of the tactical AI with a completely unbeliveable amount of troops. IMHO the only solution would be a better tactical/strategic AI and my current experience (VH/Normal/HARDCORE) don't seem to indicate that Paradox promises for 1.06 really hold: The UK landing more or less its complete Homeland army (25 divisions) in South-West-France in 1940 allowing me to eliminate them once the tanks were back from Yugoslavia and then run over an nearly-undefended UK (The Naval AI is better in 1.06 BTW, my Sealion costed about half of the German Navy).
I guess in the end this is something only Paradox can fix. A temporary fix to give "over-successful" players a challenge could be somwhat random events bringing the two sleeping "majors" (USSR and US) into the war earlier:
- UK not being able to hold Gibraltar and Suez -> Churchil promises Stalin he can keep anything he can take from the Germans east of Oder-Neisse if he joins the Allies -> USSR attacks Germany
- Half of Europe conquered within a few months (e.g. Yugoslavia falling before or in Spring 1940) -> Fearing the worst for European Democracies the US starts its Lend-Lease programm early and in a much bigger scale including "volunteer" units.
- Gemany annexing Rumania & Bulgaria instead of just allying with them/puppeting them -> seeing the subjugation of the slavic population of the Balcan as a bad omen for the Germans' real intentions towards Russia the USSR brings its industry on a war footing (and then some production boni would be justified to simulate the lowered consumer demand)
- German army in 1938 much bigger than on historical levels -> UK starts to increase its defense spendings too (i.e. more MP early) (difficult to trigger, though)
Such events would represent possible and somewhat historical reactions to an extremely aggressive/successful Germany (and the same would have to be made for other non-AI countries) which would make the live of a human player much more difficult. Just imagine having to keep a sizeable portion of your infantry at the Russian border because you never know what mischevious plan Stalin has in mind (wereas currently you can be quite sure that nothing will happen on that border till 1941 whatever you do). Much better than simply beefing up production of everyone without a believable reason.