My game Stregoneria is about to be released (proofreading is over 2/3 the way through now) and I've started extracting the mechanics out of it and compiling them into a systemless universal document to be used as the basis for another rpg I have in th pipeline and for others to use to write their own games. The ultimate aim is to have something akin to savage worlds, FATE or D20 system.

I have some questions though:-

1) Should this document be free or should I charge for it?

2) If I give it away for free, won't that be inviting the possibility of somebody using my mechanic to write a game that adversely affects the sale of Stregoneria or any other game/s I may write?

3) Should I allow designers to use the document but not be allowed to include the core mechanics in their game: i.e. players will have to buy at least one copy of the base mechanic book?

Answers to these questions and any other thoughts and considerations are most welcome.

1)  Entirely personal preference.  If you decide to charge for it, you will be getting fair compensation which is a plus.  If you give it away for free, your exposure goes way up. 

2) Giving the system away for free certainly won't aversely affect the sale of Stregoneria; it will make more people learn the mechanics and thus increase the number of potential buyers.  And quite frankly, even if you charge for the product that won't stop someone from writing a game with the same mechanics.  You can't copyright mechanics, hence the prevalence of OSR products.

3) If you want to encourage 3rd party support in that fashion, I recommend producing a piece of text specifically providing guidelines and permissions for third parties.  Valid approach, though it may take a while before you are sufficiently famous/popular to have many other designers producing supplements for your base system. 

Thanks for the sound advice.

I've made a decision that the tetractys engine pdf will be free.Exposure is probably the best thing which means that any games I write in the future (and I do have another one I'm starting on which should be available in the new year) might have a larger customer base to appeal to.

The website address is:-

www.tetractysengine.com