Natural Selection 2 Meter, a replacement for Hive on The Playground server - because the server is unranked.

Data from Wonitor were used to initialize the skill system, about 25000 rounds with > 20 players and ns2 only.
Trueskill is based on win, loss and draw, nothing else.
Marines and aliens are completely separate, as if you were a different player.

Based on ts-trueskill, read Computing your Skill for a good explanation.