The longest game I have ever played so far is FFXII. The environments are pretty large and it takes me a while to level up my characters to continue progressing through the game and so on... As a matter of fact, I'm still trying to beat it.

Longest game I ever played would have to be Final Fantasy II, mostly because there is no leveling system do you have to train your stats a lot so most of the game is just grinding.

The most time I ever spent in a single first-time play through would be Tales of Symphonia for the GameCube (now also on PS3). It was just over 225 hours, and it kept me glued to my screen the whole time. There was just so much to do in the game, and 2 different full worlds to explore. I actually have a copy for the PS3 now and played through it again recently, albeit with much less time accumulated.

Ive dumped hundreds of hours in so many games, it's hard to think which one I've played the most... I suppose I would give it to FFX. I've started multiple new games, each with hundreds of hours in them individually. The most I've spent in one save file was... Probably 500 hours or so. And no joke, most of that was probably Blitzball (Seriously...). It got to the point where I could hand the ball to Tidus, swim back to my goal, normal shoot the ball, and make it every time.

I've even hired every member from one team just to see how they play. Al Bhed Psyches are the best full team, in my opinion, mostly because of Nimrook, he's pretty much the best catcher in the game, having about twice as much catch as every other catcher at early levels.

I've even done an all female team that worked out quite well, after I hired Nimrook, and keep him benched, so no one else can use him. XD

Then FFX-2 came out and, although I really enjoyed the game, they ruined Blitzball... I was so disappointed...

I've played lots of games, but knowing which one I've spent the most hours in is hard to say.

My official record goes to Sonic Adventure 2 Battle, which I've spent +200 hours. I only know it because it appears when selecting the game file you want to load. I should also say that, out of those, more than half were collected when writing my guides for such game. Even after having it for a decade, I didn't play enough in all those years to come close to what I played in just a few months. Surprising, to say the least.

I've played it for so many hours because of the Chao World. It offers an immense amount of combinations and possibilities, and getting them all can take you not hundreds, but thousands of hours. The main story isn't anything spectacular for me, and I haven't yet managed nor tried to complete it all.

My unofficial record goes to Gran Turismo 6. I surely spent several hundreds of hours there, testing a wide variety of my cars, racing in the various modes, tuning and preparing my cars... I didn't keep track of how much time I actually played it, but it surely felt like thousands of hours.

In terms of actual games with stories it has to be Xenoblade. That is easily one of the largest games I've ever played with a plethora of sidequests(a lot of which I didn't even get around to doing) and the story itself is pretty long. Plus each area is massive. Beating the game 100% would take a lot of time to complete.

In terms of other types of games, I probably have spent a lot of time on things like Animal Crossing, Harvest Moon, Mario Party, and Smash Bros.

I don't like RPG's that much, so because of that I haven't played any ridiculously long games.

But I will say I have put like 2 weeks into fifa 16, and like 60 hours in to WWE 2k16.

But for one game, (Or mode in this case) with a running narrative, it would be  a FIFA 14 career mode I played, I forgot how long it was but it was a stupid amount

EDIT: Made it say fifa 16 instead of just fifa because if it would be just fifa it would be a LOT more.

Including MMOs it would probably be Runescape or Minecraft. Runescape has a ton of content, the only problem is that to access a lot of it you have to grind your skills up which isn't fun. I don't have a record of how much time I've spent since it's spread out on a ton of accounts. Likely though we're talking 1000s of hours which I'm sure is more than any other game I've played. Since I've been playing it on and off since 1st grade before even getting my first computer (got it in 5th grade). In Minecraft how much there actually is to do all depends on you. I never paid defeating the Ender Dragon or The Whiter any mind, I was constantly coming up with new build projects. That along with having lots of people to play with on the server extended the fun for me. I still occassionally get back into it too because it has that lasting appeal.

Now not counting MMOs it would probably be Pokemon SoulSilver. Not because it's the longest (though it's long for a Pokemon game) but when I was younger I was obsessed with Pokemon and the Pokemon games. I replayed that game more times than I can remember and also spent a ton of time doing side activities.

Skyrim also comes to mind. It had a ton of quests and also consisted a lot of making your own fun. The lesser radiant quest were also constantly generated so you technically never ran out of content. Though you did burn out on those types of quests pretty quickly which is why I kept to the bigger ones. I likely logged like 500 hours into it, enough to make the disc stop working. Skyrim is probably the 2nd longest game I've played in terms of actual content after Witcher 3: Wild Hunt that is primarily a single player game. I'm still in the early stages of that last game so I will likely end up spending a ton of time on it. It has a ton of quests like Skyrim. It also has a ton of side activities it did not have like Gwent a card game inside the actual game. While Skyrim is easier to get drawn into, Witcher 3: Wild Hunt does a better job of not making you become burned out at the game after a while of playing since it's more varied.

Probably Persona 4 Golden, I've already played for dozens of hours and haven't beaten the game yet and once you beat it, you're supposed to play it again and there would be some different changes. Even if I don't spend time level grinding and searching for stuff, it's still a very long game and I have heard some stories of people playing the game for 200 hours during their first playthrough.

Zlinqx : Oh that's right. I forgot to mention skyrim. Man, FFXII has nothing on that game. While I was eventually able to compete the main story involving the war with the stormcloaks and imperials then the world eater (Can't remember his name) there was still quite a lot to do that I never did get a chance to finish them all. This is truly the longest game I've ever played so far. I'm guessing that oblivion was just as long.

Final Weapon : From what I've heard, most fans say Morrowind is the longest in the series. I wouldn't know though since while I own the game my laptop usually crashes a little bit after starting it up so I haven't really gotten the chance to play it for an extended amount of time. I would suggest looking into Witcher 3 if you like open world RPGs with great world building like Skyrim. It's in my opinion even better than Skyrim (can't wait for Elder Scrolls 6 though).

The longest game I played would have to be between Skyrim, Persona 3 Portable, or Persona 4 Golden. I haven't even finished playing Golden yet. With Persona games, I lose interest in them after a couple months and then end up finding myself playing them again in 3-12 months.

The longest game I ever played....Honestly, I'm not too sure which one took me the longest time to complete but I'm sure it had to be Kingdom Hearts: Birth by Sleep, Final Fantasy 9, Persona 3: FES, Persona 4: Golden, Tales of Symphonia, Skyrim, or Fallout 4.

The longest game ever played for me would be Skyrim on the PS3... I remember when I got Skyrim at Christmas, I would only play it on the weekends due to school and I played it day and night when I had my spring break and summer break. The total of hours I got on the file would be over 700 hours, but that includes idle hours. 

Honestly, the longest game that I've played and beaten was probably Dark Souls 2. My save file currently has a little over 200 hours of playtime. Even if you take into account all the DLC areas, the time that I just left the game on, and the hours and hours of PvP matches that I played, it's definitely the longest game I've ever played and beaten.

I think the longest game I've ever played is Wario Land 2 on the Gameboy Color. I know there are a lot of modern games out there that are way longer than this, but I'm more into retro video games. Wario Land 2 has about 10 or 11 hours worth of gameplay if you are trying to collect all the treasures and map pieces. The game is also fairly difficult as well, and there are no time limits, so you can keep playing as long as you want. For me, this is the longest game I have ever played through 100% (which I still have a hard time doing).

If anyone know the videogame version of the LEGOLAND theme parks, then you'll probably know that there are 5 required tutorial levels and then 10 main levels. One level needs to get like 30 minutes to 1.5 hours hours to beat, because there's an inspector who keeps saying you need to change things, but he says it in riddle-like talk...

The final level takes shorter, as the inspector comes not that much, which is dangerous because if the inspector came for the last time, and it's not good again, you're lost. That inspector comes every 10 minutes, by the way.

Also, 'Level 6 - The Netherlands' is pretty annoying (Why, LEGO... Why did you guys do this...), because you gotta build you theme park, however: Aliens will take 95% of your attractions if they come. Then you gotta start all over again. Also, that inspector keeps telling what needs to be changed while you're being 'invaded'.

Probably Xenoblade Chronicles. I think I took around 60 hours to beat it (hard to say since I left the game on sometimes). I did a lot of sidequests, but not nearly all of them; just whatever I felt like doing. It was a really great game too.

According to my Steam library, the most game time I've got for a PC game is Binding of Isaac: Rebirth, with 539 hours. There's just so much replay value in the game...
Don't get me started on the 319 hours I have in Terraria, or the maxed clock I attained in Pokémon Pearl...

This I'm really thinking though since I have played so many games specially pokemon yellow, gold and sapphire. Those three games i spent so many hours in them. From when I was six years old. All the way up to 13-14 years old. Runescape did I Also spend ridiculous amount of time in when I was younger. Skyrim have not beat it on the Xbox 360, but I was so slow with progressing the main story because I found the side quest way more fun. Call Of Duty on the 360. Started to play Call Of Duty when I was 16 and still play a little today when I'm 23. Those games most be the ones I have spent most time in