I've never played a 10/10 game. 10/10 in my eyes is perfection, and no game is perfect. My two highest rated games, Red Dead Redemption and Witcher 3, are about a 9.5-9.6 for me.
Red Dead Redemption is held back from perfection by a the poor epilogue where you play as Jack.
Witcher 3 is held back from perfection by ignoring the Witcher 2 Iorveth path almost entirely.