Note: This mini-expansion requires a copy of On the Underground: Paris / New York.

In The Underground Challenge, you will compete against real Underground lines. The map starts with several lines already constructed, and you must try to beat the Underground's score.

Like the Underground engineers, you must be imaginative in constructing lines, while simultaneously enticing passengers to use your lines instead of the official ones.

If you can beat the Underground at its own game before the destination cards run out, you win The Underground Challenge!

Each round:

• Perform four actions - placing line markers or taking branch tiles, as in regular gameplay.
• Perform passenger movement.
• Perform passenger movement again.

The passenger will visit one or two stations, and the destination cards matching those stations will be removed and replaced as in regular gameplay.

Then, the passenger will visit one or two other stations, with the destination cards matching those stations being removed and replaced.

The passenger movement rules are the same as in the multiplayer game, with the following exceptions:

• If the passenger's movement is the player's choice (due to an equal number of empty spaces and lines on each possible route), the player must choose the route that gives the Underground the most points.
• If all possible routes give equal points to the Underground and the player, the player may choose any of those lines.

If your score tile reaches or surpasses the Underground's tile, the game ends and you have successfully completed The Underground Challenge!