18TN

General Information

Here are some highlights of rules in 18TN:

The Illinois Central presidency is a 30% certificate. (§3.2-5)
During the SR a player may buy a private company from another player, for any positive amount agreed upon. (§3.2.4.c.4)
A corporation can lay 2 yellow, or do an upgrade, every OR. (§4.2b)
During Phase 2 and 3 corporations can only buy one train per OR from the bank. (§4.2.5 f)
When the second 6 train is bought, all 4 trains become obsolete - phased out. (§4.2.5.1)
Corporations purchase of companies from players (§4.2.6):
- During OR1 - This purchase is for face value exactly, with a maximum of one private company per corporation, and one company total per player in the entire OR.
- During phase 3 and 4 - This purchase is for 50%-150% of face value.
When the fifth 3 train is bought all corporations with trains receive a Civil War token (which appear as an ability on the corporation charter). When a corporation with a Civil War token runs trains, the train that produces the least revenue is changed to give zero (0) revenue for that OR. After applying the effect the token is removed. (§5.1)
Besides bankruptcy and bank broken, the game can also end if any corporation's market value reach $300. In case of bank broken or market value max the game ends in the current OR. (§6)

The map differs a bit in Memphis, Chattanooga and Nashville compared to the physical game. This is for implementation reasons to make the upgrades work smoothly:
- Memphis hex used standard yellow and green city tiles. For brown and gray the P tiles are the only allowed tiles.
- Chattanooga hex uses a the C labeled yellow and green tiles. For brown and gray the P tiles are the only allowed tile.
- Nashville hex uses a standard yellow city for its first upgrade. When upgrade to green only the special N tile can be used. For brown and gray the P tiles are the only allowed tile.
The linked rules places MCR (Memphis & Charleston Railroad) in H5, but this seems to be an error in the rules. So H3 seems to be the correct location for it. Rule discussion at BGG
The 3' train is for all purposes a 3 train. It is just to make it possible to have a phase 3½.
The 6' train is for all purposes a 6 train. It is just to make it possible to have a phase 6½.
18xx.games does not support selling private companies between players, just buying. And as for other purchases from another player it is assumed that players have agreed in advance (via chat e.g.). A player that buys without agreement is breaking the game.