Accreditation
There is no central, "official" accreditation for Risk tournament play as there is with other games such as Pokemon or Magic. Without an official accrediting body, Risk tournaments are organized and designed entirely by local participants.
Organization
Risk tournaments are generally organized in one of two ways. In the "bracket" style tournament, players are placed in two-player brackets in which the winner of each game advances to the next round, while losing players are eliminated from the remainder of the tournament. In the "round-robin" style tournament, each player plays every other player at least once before the tournament is over and no players are eliminated outright.
Winning the Tournament
In the bracket-style tournament, players face one another in randomly-seeded games, with the winner of each game advancing to the next round and so on until a final champion is reached. In the round-robin style of play, players are awarded points or "wins" based upon their performance in each game; the player with the highest total points or wins is declared the champion. Some tournaments award prizes to the top player or players.
Supplemental Rules
Some tournaments choose to adopt supplemental rules which are meant to augment or supersede the official Hasbro rules. As Hasbro has no "official" tournament rules, supplemental rules are left to the discretion of individual tournament organizations. Some organizations permit unlimited free movement of pieces after each turn, or disallow those not playing a game from discussing strategy or provide advice to contestants. They may also define tournament rounds or spell out point awards for various achievements.