I am sketching out my 2012 programming project, and Im planning to make a classic fantasy RPG game.
The world design, plots, characters and all that I can make, but being a avid tabletop role-player, I would love to use a stable and tested rpg system like Pathfinder, since its balanced and interesting.
Would there be a problem if I make a game (indie dev, but still planning on selling it) using the pathfinder license ? Do I have to purchase a license? And would I able to say that it's based on the Pathfinder ruleset, or should i keep that under wraps.
All big official D&D games boast with that they are official, so doesn't this mean that unofficial games can exist too ?
It's not because I wan't to jump the lowest fence, and all storylines and the game setting will be by my own hand. But I love the Pathfinder system and actually think it could use some publicity as well.
If not, I guess I could make a Pathfinder-like system, with a few measely differences… But I would rather not, since it would feel a bit of a rip…
If you only want to use the OGL part of their rules, the answer is yes. See this previous question on Is it possible to use rules from OGL or GSL games in a computer game? You have to understand that license and adhere to its terms however. One drawback is that you may not say "Pathfinder" or otherwise claim Pathfinder compatibility if purely using the OGL.
For anything not covered by the OGL, called "Product Identity" in the legalese, the answer is "not without a license from Paizo." The public Compatibility License which allows some use of their Pathfinder specific product identity specifically does not allow for computer software.
You can also consult an IP lawyer and likely proceed without a license if you just mean to use the core mechanics. Game mechanics are not copyrightable and you may also claim compatibility with another game (this has been hashed over and settled in the courts, see Hasbro v. RADGames). Goodman Games used this exact legal right to produce some D&D 4th Edition compatible works. (There is an old oft-cited lawsuit between TSR and Mayfair that Mayfair lost regarding their AD&D compatible labeled Role Aids products - but they only lost because they had signed a separate contract limiting their rights. The OGL etc. do this too.)