I would use words like "franchise" or "series" instead "Game", Yoga.
Or you can say that all Goldboxes, from Pool of Radiance to Buck Rogers, are the same game. They even have almost the same engine!
No, technically speaking, there are this games around (according to the Moby):
1. Command & Conquer
2. Command & Conquer: Red Alert
3. Command & Conquer: Sole Survivor
4. Command & Conquer: Tiberian Sun
5. Command & Conquer: Red Alert 2
6. Command & Conquer: Renegade
7. Command & Conquer: Generals
8. Command & Conquer 3: Tiberium Wars
9. Command & Conquer: Red Alert 3
10. Command & Conquer 4: Tiberian Twilight
Everything else are not games, but addons, compilations, etc.