i haven't played games for ages but am quite the veteran:
Some few year old games
**Elder scrolls:Oblivion -Proly one of the best games ever created,a 3d first person(can be 3rd too)in medieval age.With an open world.Quite realistic even if it has magic.
**Metal gear solid:substance -I have played only this metal gear don know bout the newer(they proly are good too).Its a 3rd person stealth game.The script and generaly the game is very close to a holywood movie(in a good way).
**MaxPayne:The fall of max payne -(some might seen the movie)This too very cinematic game.3rd person shooting with dark atmosphere.
There are more games but these came to my mind.
If u play them u should do it in this orders:metalgear,maxpayne,oblivion.
There is a program that is called "game maker" as the name implies you can make ur own game,not anything shiny but still ur own,its pretty cool.
Look it up on google if u want.
For online game RPG the most popular and best is WoW.
Online shooting as u said Left for dead,call of duty etc.
The things is that when u play rpg u must chose one cause u use most of ur time ,very time consuming but good games,in action u can have several of em to satisfy you.
And i must add my fav online game.Dota (:
Its a map from Warcrat:the frozen throne (not World of Warcraft the MMO which is based on Warcraft)Wacraft is a strategy fantasy game(the best imo) and has many costum maps,DoTa is one of them,may not look appealing but the gameplay is very addictive.You should look at least for that.

There are songs by Basshunter for DoTa (u might'v heard)check in yt.
Happy gaming....
Although at some point u'll realize that games are a time waste (:
I recommend not to get involved.But i know u will =)