OGL/OGC Legalities

[Yospeck]

So I'm keen to work on my own RPG system, something I've been thinking about for a while, but I was wondering how the legalities of using a d100/d20 roll based system comes into it. Reading Wikipedia (which I didn't want to fully rely on) it seems that RPG creators are pretty much free to use any dice rolling mechanics (albeit copying the d20 system would presumably still be a breach).

Any advice?

[Griogre]

I can only speak in generalities so if it ever becomes something you are going to release you need to see a lawyer. Designers can use any Dice mechanics the wish - that type of thing isn't intellectual property. What you can't do is just copy the outcome result mechanics from some other game. So you can use a d20 to determine if an attack hits or misses, but you would be an thin ground if you said this was vs. AC or Fort or some other defense some other game uses.

However, if you were to use the OGL then you could use things like AC, etc. As you mentioned the OGL in your title if you want to make a system that uses it, you should read the license. Its not that long and is a generally understandable and would give you a good sense of what is allowed and not allowed.