Well, I've spent over 4000h on Rocket League, a game released in July 2015. I think it's a fair estimate that I've played more Rocket League in this decade than every other game I've played combined. So yeah, Rocket League.
Special shoutout to Elex who had at least a good try at giving me a new Gothic game this decade. Can't wait for the sequel.
And another shoutout to DQ11, FFXIII Saga and WoFF for keeping S Tier JRPGs alive.
If you demand respect or gratitude for your volunteer work, you're doing volunteering wrong.