Riot Games, creators of eSports frontrunner League of Legends, reportedly made $1.6bn off the game in 2015 according to SuperData Research.
The figures, determined by the market research company from publisher and payment services digital point-of-sale data, make LoL the highest grossing digital game ahead of SuperCell's Clash of Clans – estimated to have pulled in $1.3bn last year.
The figure is more than the top five console earners of the year combined: CoD: Advanced Warfare ($355m), FIFA 15 ($332m), Grand Theft Auto V ($322m), Destiny ($291m) and CoD: Black Ops III ($224m).
Other PC games to have broken the digital billion barrier last year include Korean side-scrolling beat 'em up Dungeon Fighters Online which made publisher Nexon $1.05bn, and Korean Free-To-Play Counter-Strike alternative CrossFire, which also has a strong eSports community in East Asia.
Developer SmileGate, in conjunction with Chinese publisher Tencent, made $1.1bn in the last 12 months of digital weapon sales for the shooter, which is a mainstay at major Chinese eSports events.
Other eSports titles that feature in the top 10 grossing digital products of the last year include World of Tanks ($446m), Dota 2 ($238m) and Counter-Strike: Global Offensive ($221m).
In another recent market report, SuperData Research suggested that the eSports market itself to grow to be worth $1bn in 2016, though Deloitte suggests a more modest $500m predicted figure.