TF2 Game Modes
GAMEMODES FROM SOURCEMODS DO NOT COUNT.
Control Point-Oriented
Flag-Oriented
Competitive
Training
Payload-Oriented
PVP
PVE
Escort
Zombie
MISC.

Everyone knows these
Slightly less people know these, but most still do
Only known by people with 50+ Hours
More obscure game modes, but with large dedicated player bases
Somewhat forgotten, but still has some people playing it
Basically dead, but people still stumble across it once or twice
Completely dead game modes. At most one server is running this, if at all.
Distant calls from fallen cavillations remind us of these. Barely anything about them remains.