18GM is an 18xx game development kit. It features a modular board that allows virtually endless scenarios to be developed. The game as printed includes one basic scenario, the Aurora Limited, and several variations on it. Some of the interesting ideas in 18GM are: 1. Tycoons. These are like private companies in standard 18xx, but allow various special abilities in the stock round, such as exceeding certificate limits or exchanging for shares in the bank pool or initial offering. 2. Buying on Margin: buying a share by paying half now, and half during the next stock round. 3. Making a Market: the president may reduce the price of the Initial Offering shares if the company remains unfloated.