Top 10 from 2005-2012 eh? Hmm... A couple come to mind. In no particular order:
Crusader Kings 2 - It's unique character-driven perspective on the usual grand strategy formula really makes CK2 stand out as one of the most clever and addictive strategy games of all time. It also helps that since the games release it's only gotten better with regular support and new, compelling dlc being added on a regular basis.
STALKER: Call of Pripyat - Probably my favourite shooter since the old Unreal Tournament games. Not that the STALKER series is even remotely similar, but given I'm not a huge fps fan it's something worth pointing out. In STALKER's case I just love the game for it's amazing sense of atmosphere and place. 'The Zone' truly feels alive and terrifying in a way few other games can replicate.
Mass Effect - I still prefer the first game in this series the most. Although the companion missions in 2 were great and 3 had some amazing emotional moments, 1 just felt more like an adventure to me. Plus the story in 1 is the strongest with a memorable antagonist and some stunning moments of its own. 2 *IS* really close though, especially because I love that Shadow Broker dlc.
Advance Wars: Dual Strike - My favourite DS game and probably my favourite portable strategy game. Maybe not the most well balanced game of the series, but it makes up for that with its huge library of content plus just being ridiculously fun.
Transistor/Bastion - Cheating by including both especially since transistor is 2014, but it's my list so whatever. Anyway I love me a good emotional suckerpunch and both these games deliver that in spades while also delivering entertaining gameplay and beautiful visuals, not to forget the soundtrack for both games which remain some of my favourite from any game ever.
Starcraft 2 - For a while I was super into SC2, even playing ladder and watching matches online, the whole deal. It's just an incredibly tight gaming experience that delivers a near perfect mix of challenge vs. fun in the rts genre. I haven't played the game much recently but even so it'd be a mistake to dismiss the game when I had so much fun with it previously.
Galactic Civilizations 2 - One of the best grand strategy games of its time, with a couple neat innovations on the genre plus some diabolically clever AI. Even compared to more modern or higher budget contemporaries GC2 stands out as an exceptional strategy game, especially when the expansions are also taken into account.
Mount & Blade: Warband - Damn this game is ugly, even with mods, but even so it's just got some of the most satisfying 3rd person melee combat available. Toss in the open-world style appeal of the game, very reminiscent of Sid Meier's Pirates, plus an absolutely bonkers mod community and it's just an amazing experience. Can't forget those Napoleonic Wars online battles either, utter insanity in the best way possible.
Company of Heroes - I really like this games take on the standard rts formula with its heavy focus on cover and positioning over sheer APM. The destructible environments also ensure that even repeated matches on the same map can play out very differently from one match to the other. Never did play CoH2 much, but I still absolutely love the original.
Neverwinter Nights 2: Mask of the Betrayer - NWN2 on release was a bit of a disappointment compared to the original game, but with the Mask of the Betrayer expansion the game really got a chance to shine with not only the strongest campaign of the NWN franchise (And one of the best of any game set in Forgotten Realms) but also some of the great mods which were later released as well.
