Complex? The most complex I can think of is actually not a computer game, but rather a board game: The Campaign For North Africa. It bills itself as "logistically-oriented," and heavens, does it ever deliver. 10 players (5 per team, 2 of whom are dedicated purely to logistics and rear-area operations), approximately 1200 hours estimated gameplay time to get through one campaign covering three years of warfare from 1940 to 1943. Five D-sized (559x864mm, or 22x34 in) maps were required to cover the combat area, with 84 charts and thankfully only 71 pages of rules (apparently) to go along with 1800 unit counters (though you may need to make more) and however many log sheets (on ledger-sized 17x11 sheets) you need. With the full rules in play, however, the game attempts to model the entire North African Campaign down to the level of companies, or for air warfare, individual pilots. Logistics? Perhaps the most infamous rule, but one generally indicative, requires all Italian battalions on receiving their stores to receive one extra water ration to cook their pasta, or suffer cohesion penalties - this is creatively termed The Italian Pasta Rule. Every turn, the trucks go out, their loads planned out individually to make sure your army and air force are getting what they need...but don't forget that your trucks also need fuel as well! Each turn is one week of game time, and can be expected to take around 10 hours to play through, though computers obviously help quite a bit with this in modern times. Perhaps the one thing it doesn't do, thankfully, is try to model different calibers of munitions or different spare parts for different tanks; guns is guns and pigs is pigs. The example I saw was mixing Stuarts (37mm) and Matildas (40mm) with absolutely no material (or materiel) issues. By and bye, though, for sheer complexity, I think it actually overmatches many computer games that have come out decades later.