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 multiple lines already built and you must try to beat the Underground's score.

Much like the engineering crews of the Underground you must be quite resourceful at building track and at the same time divert passengers to use your own lines rather than 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 turn:
Take four actions - with each being placing Track tokens or taking Branch tiles as in normal gameplay.
Perform Passenger movement.
Perform Passenger movement again.
The Passenger will thus visit one or two stations and the Destination cards matching those stations will be removed and replaced as in normal gameplay.

The Passenger then will visit another one or two stations with the destination cards matching those stations also being removed and replaced.

Passenger movement rules are the same as in the game for multiple players with the following exception:
If a Passenger movement is up to the player's choice (due to an equal number of empty spaces and lines involved in each potential route) the player must choose the route that gives the Underground the most points.

If all potential routes would give the Underground and the player equal points the player may choose any one of those lines.

If your Score tile reaches or overtakes the Underground's tile the game is over and you have successfully completed The Underground Challenge!