http://dreamcatcher.metroland.ru
The main functionality has been implemented. You can test it on real games.
The rating formula was taken from TOH:
http://toheroes.com/new.htm
Rn = Ro + 30 + 0.05 * (D) for the winner, and Rn = Ro - (20 + 0.05 * (D)) for the loser,
where Rn is the new rating (after the game), Ro is the old rating (before the game), and (D) is the difference between the players' ratings.
For example: if a player with a rating of 1000 (starting) defeats a player with 1100, the winner rises to 1035, and the loser drops to 1075. If, however, a player with a rating of 1100 defeats a player with 1000, the winner becomes 1125, and the loser drops to 985.