Most of the roleplayer has, at one time or another, the idea of creating their own RPG games.
Usually when you start an RPG project, there's 2 way to build it. One is working on the system and the other on the setting.
Each have their good side and bad side. Myself, I have been working on Techno-Death using my own system. I worked hard on the "How" and less on the "Where".
I think that the game is good. But it is asking of the game master to be able to create much more then a few npc.
You will have to choose what is more important for you. The rules or the setting.
If you have lots and lots (lots and lots and lots and lots) of free time, you could create both side in detail.
Beleive me, there's a lot of nice Free RPG on the web. Since I have put
Techno-Death on the web (more then 2 years), I had the opportunity to visit and read some really good work.
You want to create your own RPG games! Do you have any idea how much work it will take?
He! He! He! You can't ever imagine how much!
One way to start your own games is to use a rules system that already exist. The "FUDGE" system is one that you could use to create your games.
But if you are more into rules, then it's up to you to create something that isn't already there. And beleive me, it could be a lot of work to create a new system of rules that are working together.
Create a games is mostly a work of imagination. If you want to find a building kit that will guide you into creating your own RPG, I beleive that you will have to search hard.
The commercial company will not give you the "How to".
About me, how do I build a game? With an idea...
Don't start to work if you don't have a good idea.
I wish you good luck.