Below games have left me utterly floored for one reason or another way back when they they were brand new and I was still young. 
Tie Fighter
World of Warcraft
Ultima Online
Baldur's Gate I
The Last of Us(ok,mostly added this just to feel less old. :l ...Still an exceptional game though.)
I get it how the 10/10 thing is just an expression and all. Still I think it'd be worth talking about the following:
It is completely useless to give some hard cold number value to your favorite games. It is either meaningless or misleading. When things are put in context etc, I've never been as impressed and excited about a video game as I was when first laying hands on Ultima Online and WoW. Yet,if I were to produce some pseudo-objective score for either, I'm sure it'd be like a weak 9 or a strong 8 due to stellar amount of bugs, connection issues and various other dysfunctionality. Does that number in any way capture how awesome I think the games were? Nop!
In a sense, I think Last of Us is almost perfect. I guess it took like 22 hours or so to beat the game. During these hours, I recall like 25 minutes worth of " aw, I wish they had done this particular thing differently/better.." I think it is remarkable and translates to something like 9.9191919/10 etc.
World of Warcraft suffered from massive amount of bugs, stability issues, lag issues when it came out. This wasn't stuff that got fixed in some day 7 patch etc. Nop, we speak of several months of Bliz struggling to respond to sheer popularity of their game. If I were to give some number value to that experience, I'm not sure if it even began with " 8" Yet I loved every second of it, consider it a better game than TLOU and think of it even more fondly.