It's a grand strategy game, and one of the games I'm playing right now, so you can check it out from my list; Europa Universalis. Basically, you can choose and play as any country throughout history between 1399-1821. You can colonize the New World if you want to, you can expand your realm by war, or marriage and you can trade and stuff like that...

I sure put most of gamingtime in games like Civilization (Civ5 recently), Sim City, Anno or Rollercoaster Tycoon and Football Manager Games.

shooters

you know, when I come to think about it a little bit more, I come to realize it's probably a tie between strategy/action-adventure/party games/platformers - that sounds more closer to the truth

That sounds freakin' amazing. I've always liked games where I can control people, like SimCity.

RPG's. I've spent sooo much time on rpg's. Definitely my fav genre.

Is it like Crusader Kings II, ie a hardcore Total War without the real time battles right? I have tried to play CK II without issue, but I feel I will really enjoy it once I understand how to play it

You call it action adventure but to me it's really sandbox, i've had great fun with games like GTA 4, red dead redemption, LA noire, Mafia II, Bully (Wii), saints row 2 and 3, the saboteur, Minecraft, just cause 2, Yakuza 4 sleeping dogs and the assassin's creed series.
Although, actual action adventure and FPS comes close too. But sandbox has and always will be my favourite genre

I know Platformers took most of my gaming time this gen, Little Big Planet 1-2, New Super Mario Brothers Wii, Donkey Kong Country Returns, PID, Mark of the Ninja etc.

Well, you're not controlling people per say, more managing the country and armies and stuff like that... But yeah, it's kind of SimCity on a grander scale :p