General Strategy

• Defender of the Crown
• Lords of Conquest
• Wargame Construction Set

Turn-based

• Alpha Centauri
• Age of Wonders series
• Battle Isle series
• Chaos,Lords Of Chaos,Rebelstar series
• Civilization series
• Colonization
• Dominions2
• Etherlords series
• Fire Emblem series
• Galactic Civilizations
• Heroes of Might and Magic series
• Master of Orion series
• Silent Storm
• Space Empires series
• Stars!
• Superpower series
• VGA Planets (for play-by-email)
• WarLords series
• Worms series
• X-COM series

Real-time (RTS)

• Age of Empires series
• Age of Mythology
• Black and White
• Blitzkrieg
• Command and Conquer series
• Commandos (game) series
• The Corporate Machine
• Dark Reign
• Dune series
• Empire Earth
• Europa Universalis series
• Ground Control series
• Myth series
• Populous series
• Railroad Tycoon
• Red Alert
• Simutrans
• StarCraft series
• Syndicate series
• Takeda
• Total Annihilation
• Transport Tycoon
• Warcraft series

Please note that this is an incredibly shortened list, which only list some popular series, and indeed leaves some of those out too.