http://store.steampowered.com/ I'm not sure what to say about this site/platform well, there are a TON of games , some free and some not. The first thing i'd recommend you to buy here is Half-Life 2 because once you have that you'll be able to play the free mods such as: "Pirates,Vikings, and knights II","Zombie Master" and "Zombie Panic!". The're are also plenty of demos and F2P games which don't require you to buy anything to play them.
And heres something for you "techies" http://steamcommunity.com/workshop/ If you're any good with 3d modeling you may want to look into this. Steam workshop lets you create anything you want for Skyrim and team fortress 2.
D.Gray-Man - Action/Adventure/Comedy. Towards the end of the 19th century Allen Walker (my profile pic) joins the organization of Exorcist that destroy the evil beings known as akuma which were created by the Millennium Earl by using the suffering souls of the dead. 103 Episodes
History's Strongest Disciple Kenichi - Action/Comedy/Martial Arts. About a young "weak" kid named Kenichi. one day he gets challenged to a fight in his karate club. A new classmate Furinji Miu invites him to her dojo "Ryouzanpaku" for training in several martial arts to prepare for the fights to come. 50 Episodes
Katekyo Hitman Reborn! - action/comedy. About a boy named Tsuna nicknamed "no good Tsuna" for his ability to fail at just about everything. He is chosen to lead The Vongola mafia and is appointed a "tutor" to train him. He quickly learns that both him and his friends are in danger so he tries to become stronger in order to protect them. 203 episodes.
DeadFrontier MMO - A zombie mmo in which you see from a bird's eye point of view. If you didn't know about this game, you must not be a fan of zombie games.http://deadfrontier.com/
Its been... I don't even know how long now... We've spent weeks barricaded here in the pawn shop and we're running low on just about everything... Dr.Maxwell's condition has taken a turn for the worst, what the hell will we do without a doctor?... Tyberious is handling all this too well, he has to be up to something again... Hes still refuses to let anyone see whats in that satchel of his....What if that smug bas***d has the vaccine? what should I do? Maybe I can steal it while hes asleep... We're heading out tomorrow to find medical supplies... I hope Maxwell can last that long.