Well to The Game Awards it seems to mean the best game released from around November 20 to November 20 the next year even if the calendar year doesn't line up. I find that irritating.
The Academy Awards gets it right with January 1 through December 31 which is why their ceremonies are in February or March.
It may vary based on different awards shows or individuals, but for many it simply means the best game released in a year.
Right now, for me, that would either be Mario Kart World or Donkey Bananza (once I finish the final boss).
Lifetime Sales Predictions
Switch: 161 million (was 73 million, then 96 million, then 113 million, then 125 million, then 144 million, then 151 million, then 156 million)
PS5: 122 million (was 105 million, then 115 million) Xbox Series X/S: 38 million (was 60 million, then 67 million, then 57 million. then 48 million. then 40 million)
Switch 2: 120 million (was 116 million)
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima
