This is highly inspired by the on-line team based action game called Tribes. It is THE best game as for team work won, highly customizable, and highly, very highly replayable. It rocks,and that is all. I did this using #2 pencil and these nifty waterproof/fadeproof pens called Micron by Sakura Color Products Corp. of Japan. Buy them, they are most useful, especially if you use water colors to color and want nice dark lines!