DosBox & WinApple are two emulators I use @ work. In our off season there is time to kill, and old strategy games fill the bill. Not to mention the computer I'm using is built on an H8SSL motherboard, 8meg of video ram onboard. No graphics intensive games here. Nope. Two of my favorite Apple 2 games are Guadalcanal & Bomb Alley. BA is the Mediterranean theater, played from the Axis viewpoint. All the Italian navy & German u-boats are available, and I have won the game by having the DAK take Alexandria. I'd like to play a more land intensive version, hence Desert Rats (also downloaded Rommel: Battles in North Africa).
If you've ever played Avalon Hill's board games, you know the rules are intensive. Same with some of the old Strategic Simulations games. Trying to play one w/o a rule book sux, I don't have THAT much time to kill.