So many good games on sale today.
Divinity: Original Sin: a great resurrection of the CRPG genre. I highly recommend getting the Collector's Edition that includes two copies and giving the other one to a friend also loves the genre. I don't think there has been another game outside of playing with a DM in Neverwinter Nights that has recreated the feeling of a pen and paper RPG experience like this game has. Also, pick up Wasteland 2 while you're at it, and your life will be complete.
ARMA3: If you dedicate enough time and find a clan of like minded players, it can provide one of the most unique and atmospheric gaming experiences ever. Nothing compares to having a real person orchestrating the mission you are on for a group of 30+ players all working together. This game definitely rewards the time and energy you put in to it.
The Secret World: Single handedly revived my interest in MMOs. Wholly unique setting, really well written, even enjoyable in small doses and has no treadmills or grinding. No monthly fee and is still regularly updated with new content that continues an overarching storyline. I also love the aesthetic of a bunch of hipsters joining the illuminati to take on C'Thulhu. It's also capable of being just as humorous as it is grim and dark. Also, the level of character customization is similar to Guild Wars where you can choose 2 classes to combine and mix and match skills with unlimited re specialization. Quest design is also quite original and often times requires a great deal of puzzle solving that can even require you to investigate and find clues outside the game.
Ultra Street Fighter IV: This is the best fighting game on PC, and in my opinion, is one of the greatest achievements in animation and art direction from last gen. Pick a character you like based on how they look, not on balance or tier lists. While there is nearly no tutorialization in the game, there are several sources in the community to get information on how to improve your play if you're interested in taking it to that level. Otherwise, mash with your friends and you'll still get the same amount of enjoyment, if not more.
Age of Wonders III: Really great amalgam of Heroes of Might and Magic and Civilization. Turn based battles on the scale of something like Total War. Amazing graphics for the genre it's in and really impressive in scope and balance. Game sounds more complicated than it actually is, and is almost instantly familiar to fans of any of the three games mentioned before.