Since april 2001, monthly medals are awarded for the best performances in MU games.
Since july 2001, monthly medals are awarded for the best performances in SU games.
MU medals are awarded to the highest scoring players according to this formula: (PCT*ALL*ANO*(NDO)^1/4)/100 Here, PCT is the winning percentage, ALL the total score of points in this game in this month, ANO the average number of opponents in a single game (so a 4-player-game would yield 3) and NDO the total number of different other players you played this game against.
SU medals will be awarded for the best single result in the respective game during a calendar month.
Additionally, there is a medals table for both kinds of games for each month, and a total table over all months.