So were several of the Command & Conquer games (long live RA2's French Grand Cannon), and Age of Empires 2 had those great forest maps where well-placed walls could shut down half the land. Strangelove, Supreme Commander was a turtle's dream. Though you had to turn off nukes in the sequel if you didn't want every game to end like Dr. And if that wasn't enough there were also mobile anti-air guns that were, at the lowest tech level, better value for money. For air defense you'd start with straight-up anti-air turrets, then go to anti-air flak artillery, before finally bringing out the big guns of anti-air SAM launchers.
It spoiled you for choice with different kinds of turrets for air, land, and sea, as well as variations for each of the three tech tiers. Supreme Commander was a natural fit for turtling, especially if you downloaded one of the mods that made the AI more threatening.
