The Airborne Assault series is the absolute best real-time representation of high-level (operational level) strategy and tactics in gaming, and I will accept any challenges to the contrary. The basis of this argument is on both the implementation of command and control/chains of command, and on the presence of time as a crucial element in planning strategy in the form of order delays. You aren't playing a godlike entity with full absolute control of your units, you're a high-level commander.
(HistWar looks interesting, but it not yet proven. This series, on the other hand, has been virtually getting unanimous critical acclaim and awards from the wargaming community and press)
It is niche PC games like this that will ensure that, despite growing somewhat away from mainstream PC gaming in the last few years - I will always be a PC gamer.
As much as I love HoI2, what I consider the best WW2 game isn't HoI2; it's Airborne Assault: Conquest of the Aegean (its predecessor in the series, Airborne Assault: Highway to the Reich, is in a similar vein, but covers Operation Market-Garden).
Why is COTA a good WW2 game? It's not Hollywood-style, and it doesn't just implement the WW2 setting just for big explosions and drama. Instead, it uses the setting as a strength of the game, crafting historically accurate scenarios and putting you in the shoes of the general of a particular battle. It's of an operational scale (thus smaller than HoI2), which I think allows for tigher design. COTA covers the battles of Greece, Crete, and a hypothetical invasion of Malta.
It's an operational wargame. It's real-time with pause, but plays nothing like a RTS. It tries to be as accurate as possible, avoiding as much gaming conventions as it can - a pseudo-simulation of sorts. How does it do this? I'll present some points posted by someone else on another forum (MarkShot) who does it much better than me, and I absolutely agree with him.
Summary:
1) The Order of Battle actually matters. Multi-level chain of command means you can macro- or micro-manage as much as you want. The beauty of it is that the more you micro, the more HQ becomes overwhelmed, learning to longer order delays, so you quickly learn to deleguate.
2) AI is very capable of carrying out your macro orders. In setting your orders, you set out different parameters, and the AI carries them out competently. There are a general view of what order settings you can have available on the left:
3) Order delays means that this CAN'T be a twitch fest, even if you wanted it to be. Every order you implement (because you control battalions and regiments and above, and not single squads or units) takes TIME to be carried out. It takes time for your units to organize themselves and prepare. What this means is that you have to plan out ahead, and anticipate the enemy's plan as well, taking into account various possibilities as well. You can't overcome setbacks by clicking wildly. From a gameplay perspective, that makes it very challenging.
Why does no one play this around here? Well, you basically play on a 2D map and manipulate little squares around. You don't see lots of bells and whistles. Despite that, the look is clean, the interface itself is ace and very functional, and it performs really well. It's a big shame, really.
I dug the games so much, I went out and bought some books on Market-Garden and the Greece/Crete operations to read more on them. That's what WW2 games should do - stimulate the player to learn more about the conflict.
In any case, the upcoming game in the (renamed) series is Command Ops: Battles from the Bulge. It'll actually have a demo, so maybe people will finally try it out.
I usually hugely favor turn-based over real-time when it comes to tactics/strategy game. In fact, I will always ALWAYS pick a turn-based tactics/strategy game over a real-time one given a choice - the sole exception being this series. The authenticity that the system brings to the depiction of operational-level strategy and tactics (any such emulation in a turn-based system would be fairly abstracted) is so significant to me that I will even forgo my turn-based bias.
http://www.matrixgames.com
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I also really like EU3 (in some ways I'd even favor it over AA, such as co-op), Men of War (awesome implementation of Rambo-style action and tactics/squad controls), and Close Combat.