The Secret World has seen a resurgence of player activity since getting rid of its subscription requirement and adopting a Guild Wars-like content cover charge model.
In a stock notice reported by GamesIndustry, Funcom said activity has jumped by 400% since the subscription requirement was killed off in December.
Although the MMO's client still commands a hefty cover price, and future DLC will come at a cost, Funcom said it has been joined by "thousands" of new players.
70,000 copies of The Secret World were purchased in the last four weeks, which is a 30% rise in total sales.
Funcom didn't give hard numbers on revenue, but CEO Ole Schreiner said the game is "building the basis of a very sustainable business" now that it has done some major restructuring.
The Secret World sold poorly at launch, resulting in mass lay-offs at Funcom, including the MMO's lead designer, and a decision to focus on smaller titles from there on. Funcom tried to stick by subscription fees but admitted it should have made the game more commercially oriented. Nevertheless, Funcom is keen on sticking by the game's principles.