I have played many great games, and so my answer will surprise you.
Minecraft.
Now before you get too confused, yes, there are other games out there that are a better this or that, but minecraft literally is infinite.

With mods minecraft can be any game you want it to be, from a zombie FPS to space adventurer to puzzle maps, minecraft is like the ditto of the pokemon world. It can change to whatever, and as such I consider it to be the best because it can be whatever you want.

Just a fun little way of looking at that for ya.

(my other answer is a game called Vampire The Masquerade: Bloodlines, as it is one of my favorites and despite the age is still amazing, however I'm sticking with minecraft, as there are ways to be a vampire there too)

Best game ever for me growing up was Legend of Zelda: Majora's Mask. It was the first game that ever gave me a sense of urgency and a feeling that I absolutely NEEDED to do all of the side quests to help everyone. It was amazing getting to relive that game all over again on the 3DS.

Mine has got to be ALL of the Bioshock games on my Xbox 360 XD I'm looking forward for the next game come out soon!

FALLOUT!!!!!! NEW VEGAS TO BE SPECIFIC

My favorite game is either Grand theft auto San Andreas or The witcher

The Legend of Zelda Ocarina of Time

Agree