While some companies don't enjoy fans making their own games out of a franchise, there are quite a few Sonic fan games out ...
Call of Duty has one of the largest and most consistent player bases which might make some curious as to how many people are still playing Modern Warfare 2 and Warzone along with Modern Warfare 3.
The last update known sales number for Overwatch was 50 million in 2022 before transitioning to 2, and it looks like the free-to-play model has drastically increased its player base since then.