Edit.. missread the OP. Can be deleted.

For a single play through in a non RPG: Twilight Princess. I clocked 60 hours in that.

Depends. Are we counting games with no end? In that case I've spent hundreds of hours on a single playthrough in Transport Tycoon and Civilization.

If we're explicitly talking about games with an ending, then probably Ocarina of Time. There's just so much to do in that world, my first playthrough must have lasted about 100 hours.

If we're talking playtime with replays, then it's Mega Man X. Played that sucker hundreds of times from start to finish, more than a thousand hours in total for sure. It's the only game where I'm able to pull off something that could be considered a speedrun. Still far away from what the pros do, but I get through the game pretty fast without taking a single hit.

I don't know, thought it was hack n slash :p

I think I have around 500 hours between two saves in Metal Gear Solid Peace Walker. Deleted the first one in a fit of anger over a ridiculous reason.

Over 90 hours in Doom 2016 for exploring easter eggs & references.

Probably Super Mario World (SNES) when I was a kid, it took me 4 years to beat it.

Probably the 70 or 80 hours in some Zelda game to 100% it.

I think over 80 hours on both Lego City and Windwaker HD, though that includes a lot of casual driving around the world with my son and getting 100% on Lego and lots and lots of listening to music on Windwaker. Also I get astuck a lot on Zelda games hehe.

Almost 300 hours in MGS Peace Walker HD, trying to S Rank every mission, get all items and co-op/versus. I had a blast with it. But MGSV tops it, i have probably 400/500h of play time. Thats due to exploration, getting 100%, S ranks and mission tasks, with some Fob defenses/attacks in between. Not the MGS it could have been but one of my favorite games ever. I had way too much fun with it, wish there was co-op as well.