Most hours spent on one game?

Garry's mod I have more 2000 hours played in this game, very fun

1527 hours on Team fortress 2
765 hours on Warframe
I don't have an exact number of hours for Minecraft but since I am playing from 2012-2013 I assume atleast 2500 or 3000 hours

World of Warcraft definitely I got 4500+ playing since 2015

Minecraft without a doubt, but CS:GO is not far away i bet. When you minecraft you can't stop, atleast if you are undr 13 ;/ No longer perhaps

i spend 6 hours a day for 6 months i think . i was addicted to cod i think

CSGO like atleast 1k hours on that. Moved on to several shooter games. Overwatch, R6, Apex, and various ones.

championship manager - CM - great old soccer manager - months, years ...

since minecraft does not record playtime, i have to guess here. but i am pretty sure it is minecraft and i guess i have around 4000 hours in it

Pokemon X & Y. I think I logged at least 1500 hours in both those games combined.

Garry's mod. I know it seems like such a shit choice, but i really like the aspect of sandbox and being able to make any kind of scenario you want with it, I have about 5K since 2013