So a 10/10 for me isn't perfection because that just makes the rating unattainable, to me its a game that I absolutely adore and like a favourite movie, memory or book it's nice to revisit it occasionally.
Dark Souls 1 (and maybe 3).
I haven't finished 3 yet (though I suspect I'm close) but I adore the game and the franchise as a whole. DK1 was amazing with some of the tightest mechanics I'd experienced in combat and a beautiful, deep story that made me ravenously consume information provided to me, reading every item description and exploring every nook and cranny to find out more. I loved the story, the characters, the combat and the world design. Its interconnectedness is cunning and I really like that after hundreds of hours of experience you can trace convoluted routes that take you to wherever you wish to be.
Spec Ops: The Line.
Yeah, it floored me. I knew that the game was meant to have some grand twist and I cottoned on early as a result but it still didn't stop me. While the ending didn't have exactly the right hit on me since I played it to know what would happen and not to be the hero it still stung and the deconstruction of the shooter genre was excellently cruel if imperfectly done.
Pokemon...?
I wouldn't know what to say other than the most recent. I just love the pokemon metagame and have spent years building a sprawling team of dozens of maxed out, trained and specced pokemon. My Jolteon that has been with me for years holds a surprising amount of affection from me and I just adore the game series, its exploration is fun, the expanding movesets, typing and designs admittedly enthral me. Love it.
Bioshock
I didn't play System Shock back in the day, I'd read Ayn Rand's works by this point and it was a beautiful deconstruction of her world with a fun mechanic base and cool world. Has its flaws and the combat in 2 was generally better (ashamedly I have yet to play Infinite) but I've never had so much fun with telekinesis.
FF...9?
I'm not sure, I love a lot of the games in the FF series and find some of them intolerable. IX captivated me, it was my second game in the series and I love it today as much as I did when I was a kid. There are issues (too many status types for one) but I still adore the game and replay it often. I loved VII (my first FF), I loved XII (the politics and the story and the themes) and enjoyed X greatly but IX was the one I love the most, even if I played XII more back in the day (and helped write a guide for it).
Journey/Flower
They do what they do beautifully. I love Flower, I still play it to detox from the hardest games in my library sometimes, I love being high and floating about as a petal. It's awesome. Journey was the centre of my Philosophy of Art dissertation, a beautiful game in its own right and something I've explored the themes of endlessly. Beautiful games.
Binding of Isaac
I'm not a huge indie gamer and there aren't that many roguelikes that I play but Isaac...I've played Isaac so much. I've finished the game almost 3 times I think (as in, completely completed) and will likely do it all again. Beautiful, ridiculous fun. Shoutout to Super Meat Boy as well for being so damned beautifully difficult I still haven't done everything on it, not even close.
I'm sure there are more, these are the games I'll play forever.