FIVE PLAYERS MATS FOR TERRAFORMING MARS
Holds all the pieces in place, no more slip and slide.
When I was reading the review of Terraforming Mars when it first came out I was thinking "Why are all these people complaining about the slippy mats? Surely it can't be a big deal".
Then I bought my copy and realised it is! Even the slightest nudge seems to send the cubes sliding. "Now was that on 2 or 3?"