Best game of the decade? -> Witcher 3. This decade gave a lot of good games but for me, nothing comes close to W3.
Worst game of the decade? -> Duke Nukem Forever. I waited forever for this game and it was utter crap.
Biggest disappointment of the decade? -> The ending of Phantom Pain. It pains me Kojima couldn't or wouldn't complete it and MGS got robbed off the ending it deserved.
Game that changed gaming of the decade? -> PUBG I think. Not a fan but the influence it had is undeniable.
Game that you played the most? -> Witcher 3.
Soundtrack of the decade? -> Persona 5 OST
Story of the decade? -> Witcher 3
Game that you will continue to play during next decade? -> Deus Ex(Original). I am addicted to it so I replay it every 2 or so years