WarBirds Dogfights

VS

Second Life

WarBirds Dogfights is a long-running online air combat simulator series best known for its popularity in the early 2000s. The 2016 release is niche, appeals to simulator enthusiasts, and is now quite old. Given its age, niche genre, lack of major publicity, and publisher/developer info, it's likely to have a small but dedicated player base, estimated around 50 daily active players.

Second Life is a long-running sandbox virtual world released in 2003 by Linden Research. Its mainstream popularity peaked in the late 2000s, but it retains a loyal user base thanks to its unique user-created content and social interaction. It is still supported and receives regular updates, but its daily player base is much smaller than during its peak years. Current estimates place its daily active users in the tens of thousands.