Well this is my list
1.Max Payne
2.Max Payne 2 The Fall of Max Payne
3.Mass Effect and Mass Effect 2
4.F.E.A.R. Series
5.BioShock and BioShock 2
6.Fallout 3(buy the game of the year edition it has all DLC's) and Fallout New Vegas
7.Dead Space and Dead Space 2
8.Company of Heroes series
9.StarCraft(Brood War expansion pack) and StarCraft II
10.Half Life series

All are good games, they never get boring, there are, a lot more both I don't think that you are ready to give all your money just for video games.