An R implementation of the TrueSkill Algorithm (Herbrich, R., Minka, T. and Grapel, T), 
a Bayesian skill rating system with inference by approximate message passing on a factor graph. 
Used by Xbox to rank gamers and identify appropriate matches.

http://research.microsoft.com/en-us/projects/trueskill/default.aspx 

Current version allows for one player per team. Will update as time permits.  
Requires R version 3.0 as it is written with Reference Classes.

URL: https://github.com/bhoung/trueskill

Acknowledgements to Doug Zongker and Heungsub Lee for their python implementations 
of the algorithm and for the liberal reuse of Doug's code comments (@dougz and @sublee on github).