Oh, the PS2 is going to be a hard choice...
PC:
Mass Effect. The whole trilogy, realistically, but if I have to reign it in then I've probably spent the most time with the very first one, with
2 coming in closely behind it. There is very little about the franchise that I don't love, and those problems I have are overlooked simply because of how much I enjoy them whenever I get into them again and again and again. It's been just about the only game, especially a full series, released in the past seven years that I've played completely more than twice.
Nintendo 64:
Banjo-Tooie. I thought
Banjo-Kazooie was amazing. I wasn't even prepared for how mind-blowing
Banjo-Tooie was going to be and still is to this day. It's aged remarkably well, all things considered, and aside from the silly first-person segments they shoehorned in because Rare was having too much fun with
Goldeneye at the time, everything about it just feels so much better than the first game. The pinnacle of third-person collect-a-thon platformers, in my opinion, and I'm sad that it's a genre which has all but died out these days.
Playstation Vita:
Persona 4 Golden. You might say I'm cheating because
Persona 4 was a PS2 game, but I never played it on the PS2, so hah! But in all seriousness,
P4G alone justified the cost of purchasing a Vita to me, and also caused me to buy
Persona 3 Portable and currently be very excited for both
Persona Q and
Persona 5. It also bumped its way up to sit alongside
Final Fantasy IX as my favorite JRPG of all time. Speaking of which...
Playstation:
Final Fantasy IX. There are only two things I think are inherently bad about the game - The relatively slow combat when compared to other
Final Fantasy games of the time, and Quina. The story goes mad three-quarters in, but that's par the course for most of the
Final Fantasy games I've played and the way it's told is just magnificent. Basically,
Final Fantasy IX is the reason I hate
Final Fantasy XIII.
Playstation 2:
Kingdom Hearts II. It's a very, very close tie between that,
Kingdom Hearts, and
Okami, with
Final Fantasy XII trailing in behind. But, especially after having recently played
Kingdom Hearts II Final Mix for the first time, it just reaffirmed everything that I loved about the game when I played it before. It's hard to even express my thoughts on that title, really.
Special Extra -
Playstation 3:
I could cheese it and say
Okami HD, but I don't think that's really fair since I
was one of the five people on the planet who bought
Okami back in 2006. So instead I'll go with...
Metal Gear Solid 3 HD. I had never played any of the
Metal Gear Solid games before 2011, but after watching a Let's Play of
2 and
3 I knew that I had to experience the franchise for myself, and the release of the HD collection gave me a great opportunity to track them all down on a single system. And what an experience it was. Hideo Kojima is a brilliant madman with either a terrible editor or a team that doesn't know when to tell him to cut back on the exposition. Or both. But either way, I love the
Metal Gear Solid franchise for all of its strange quirks and eccentricities in writing just as much as I love the stealth gameplay and all of the little easter eggs.
Extra Special Extra -
Sega Genesis:
Sonic the Hedgehog 3 & Knuckles. That franchise basically started it all for me. There was no game I played more when I was younger, no game I've repurchased more times on other platforms, no other game that has somehow been a constant fixture in my life.
Honorable mentions go to
Halo 2 on Xbox,
Pokemon on Nintendo handhelds pre-3DS, and
The Legend of Zelda: The Wind Waker for Gamecube, which holds the distinction of being the only
Zelda game I've ever completed.