Knud H. , you can play almost any game you want on Roll20. RPGs, Wargames, Board games, and Card games are all possible. :) Currently the most popular RPG games on Roll20 are D&D 4th edition, D&D 3.5 edition, and Pathfinder (a variation on D&D 3.5). You can use the SRD's and PRD's for 3.5 and Pathfinder so that basically makes them free although you can buy Pathfinder PDFs and books and you can probably find used 3.5 books. WIth that said, you don't have to limit yourself to D&D type games if you don't want to. There are many other games being played on Roll20. Here are a few links to the SRD/PRDs 3.5: <a href="http://www.d20srd.org/" rel="nofollow">http://www.d20srd.org/</a> Pathfinder: <a href="http://www.d20pfsrd.com/" rel="nofollow">http://www.d20pfsrd.com/</a> and <a href="http://paizo.com/pathfinderRPG/prd/" rel="nofollow">http://paizo.com/pathfinderRPG/prd/</a> - Gauss