I just building this game table, I used an 8x4 medium density board. I first did the roads out of foam core, lightly cracked them up a bit, fixed them in place. Then I built the craters next to the roads out of paper mache and foam pieces. After all of that I plastered the table with a plaster of paris, silicone, texture and black paint mix, once that was able to dry for about 24 hours I came back and painted it with three different washed down colors, black, rust and the a ligher grey to give the higher areas a decent lighting effect, its kind of hard to see on the video... but its there. Leave comments and like if you think I did a good job.
http://www.youtube.com/watch?v=ZCnYcNY7xuA