Starcraft II, any of the Microsoft Age of Empires/Mythology series. Total Annihilation. Hearts of Iron III/IV - All pretty much made me the man I am today. I know I've surpassed the 10,000 hour mark I am reluctant to admit.
Being good at Starcraft combines skill from poker, chess and piano playing. I want to retire from real work eventually and spend a few hours a day in it.