Well that is all a matter of opinion. Tell us what type of games you like and we can better build you a list...
If you are into MMO/RPG games then I would def recommend WarCraft - if not into that you could check out Sims - still not your cup of tea, maybe a shooter game, so try Titanfall or Call of Duty.
I could keep the list going as their are lots out their from 2014 alone that were amazing games, but don't want to bore you with games you may have no interest in.
As mentioned it really depends on what your preferences are, you'll have to elaborate a bit more but personally once I build my gaming PC I'll be going for Arma 3 and or the DayZ standalone.
Some of the game I like on PC are:
Left 4 Dead 2
Counter Strike: Global Offensive
Minecraft
Rust
Skyrim
Sims 3
Fallout 3
7 Days To Die
Team Fortress 2
Borderlands 2
Payday 2