TF2 Clause

A term used to define a game that, despite not getting a lot of attention from its developer, retains a large playerbase.
Named after one of the best examples of such phenomenon: Team Fortress 2.

Randy: "Skyrim is a dead game, why do people still talk about it"
Alex: "Because it's a TF2 Clause."
Randy:

Alex: "It maintains a playerbase without getting much attention from the devs."