Team Fortress 2 - #1
I'm sure you understand.

I am not

your cha0ticz on dm6?

I understand

"The following table represents a small selection of the top games with Achievements on Steam, as ranked by number of total unique players (i.e. the number of Steam users who have played the game at least once) as of July 1, 2018 and as collected by Steam Spy's Sergey Galyonkin. The data was extrapolated from the Achievement percentage data provided by Steam's API, so games that do not have developer-set Achievements are not represented."

i.e. Once I've played Overwatch, got tired of it after 2 hours, uninstalled it and requested for refund.

Ye. This is completely meaningless to determine how well a game is doing.

pls don't make me look at quake champions

Holy shit @ Pubg. Like, this is the entire history of steam, all the way back to 2007 or whenever it started appearing, with many of the triple-A titles you can think of in this timeframe releasing on steam and a game that's not even one year old is almost at the top of the list. PUBG has been played by 3x as many people as Skyrim and GTA V.

edit: Wait, I don't think it's complete: Tribes:Ascend is nowhere to be seen in the CSV file, which definitely isn't right. I'm certain that game has been tried out by at least tens of thousands of people.