I'm sorry to say I doubt a tutorial like that exists.
Making games themselves requires some time and patience, even within a language as simple as DarkBASIC. Therefore making a "game maker" within an already very suitable "game maker" (DarkBASIC) would prove to be quite a large challenge.
Although this obviously depends on the type of games that you want your "game maker" capable of producing and your programming skill
Now...making something like The Games Factory
(http://www.clickteam.com/eng/tgf2.php) is certainly possible within DarkBASIC. Something as complicated as that would be a very large project and would take a single coder a long time to make...
I used to own a copy of the original THE games FACTORY and it was a fun introduction to making games. (Shame I never had net access back then

...).
It was very poweful...you could make Scrolling Platformers with NO PROGRAMMING - you would use a very easy to use Event Editor where you would just point and click and it would handle the code behind the scenes. It made creating animated sprites very easy using the simple animation editor. You could import AVI & Quicktime movie clips and control them with the Event Editor. The same for sound, you could set movement types, what would happen when things collide....the list goes on!
Creating something as complicated as DarkBASIC would definitely require years of experience and some serious coding skills (Lee Bamber is certainly due of some credit for creating DB) and you would probably need to use something like C++ to make sure your "game maker" runs as quick as DarkBASIC does.
What I am hinting at here is, I do not doubt that it is possible to create such a thing as a "game maker" in DarkBASIC...the question is:
Why would you want to?
DarkBASIC has opened up game creation to many people (such as myself who want to create games as an "enthusiast/hobbiest"), but do not want to spend months (perhaps even years) learning C++ and all the dozens of libraries that you would need - just to do some basic game.
Hopefully that has revealed the type of dedication you would need to put to a project like that.
However, please don't be discouraged from programming. Its a fantastic way to be creative.
If you really really want to use DB to create a "game maker" then I would suggest starting simple and be realistic in what you want to achieve.
I see from your other posts that you started coding an RPG, how did you get on with that?
Best of Luck!