This year's 18xx event will allow play in 1830, 1856, 1861, and 1870, as well as 1880, 1846, and 18EU (as voted in by email). The 18xx event will be held on Saturday and Sunday of the pre-convention weekend. There will be four preliminary rounds (three on Saturday, one on Sunday), with a semi-final and a Final round on Sunday. All games can be played in any prelim, but it is suggested that shorter games be played during the Sunday prelim, and longer games during the last Saturday prelim. Emphasis will be placed on making all games 4-player whenever possible, as this will be the format for the semi-final and Final. [For example, if 23 players appear for a round, with nine players for 1856 and 14 for 1830, the games will be apportioned as follows: 1856: a 4- and a 5-player game; 1830: a 4-player and two 5-player games. If eight of those 23 players want to play 1856, the division becomes 1856: two 4-player games; 1830: three 4-player and a 3-player game.] Players will be placed in games at random, except that players that have met in previous rounds will be moved where possible.

The top seeded winners, plus alternates, of all preliminary rounds will advance to the 16-player semi-finals Sunday afternoon. If there are fewer than 16 preliminary round winners, enough runner-ups (seeded by the MESE criteria given below) will advance to make 16 semi-finalists. If there are more than 16 winners that attend the semis, one or more semis will be expanded to include them. Semi-finalists will be seeded by the MESE criteria and placed in the four semi-final games according to 1st-8th-9th-16th, 2nd-7th-10th-15th, 3rd-6th-11th-14th, and 4th-5th-12th-13th. Players in each semi-final game will vote on which game to play, by secret ballot. Any game is eligible for voting. Once a game receives a majority of votes from the semi participants, it will become the designated option for that game. If the players cannot agree to play that game, they will play the default game of 1830 (classic). Voting among the finalists for the final game will be conducted in the same way. The winners of the four semi-final games will advance to a four-player final Sunday night. If necessary, semi-finalist runners-up can move up (again, seeded by percentage of the winning total), to ensure a 4-player Final.

The WBC Multiple Entry-Single Elimination (MESE) seeding criteria are: 1) Most wins; 2) Win in first heat entered; 3) Win in second heat entered; 4) Win in third heat entered; 5) Win in fourth heat entered; 6) percentage of winning score; 7) average finish in all heats entered; 8) high dice roll. For all ties, criteria will be checked in order.

Optional rules in force for each game will be announced by email to all who inquire, and before the start of each round. The time limit for the first three preliminary rounds, the semi-final, and the Final round is 5 hours, with more time available in the last session Saturday night. No stock round will begin within 30 minutes of the round conclusion. In the last 15 minutes of a round, only route running, revenue collection, and train purchases may be conducted (tile placement, tile upgrade, or token placement will not be permitted). Unless there is a player bankruptcy, rounds conclude at the end of that series of operating rounds.