MMORPG:
Theoritically, mmorpg is possible with dark basic professional. Even with darkbasic it's possible(once it's enhanced), but that depends on your defininitoin of mmorpg. Most people think of mmorpg's as everquest, and FFXI. A mmorpg is simply, a game that hosts enormous amounts of people on one server(Called the Client). With DBP, it's possible to get up to 255 people in one server.
You'll need
-Experience
-Good coding practices
-A strong server to host the game
-Funds, to keep the server running
-Time, to maintain the game.
Remember, after you program the next mmorpg, it doesn't stop there. In fact, you'll end up with more customer support,updates,etc.
Gravity:
I believe there are examples in the help files of DBP.(maybe dbc)
Good beginner projects :
Pong- Check the codebase for numerous examples.
Monster Hunt- full source in tutorials.
Binary moon(Hover racer)- full source in tutorials.
http://darkbasic.thegamecreators.com/?f=tutorials (the tutorials)
RPG:
There are currently no direct tutorials on making an rpg with darkbasic. BUT, never fear, because I have a solution.
http://developer.thegamecreators.com/?f=t01/3d_tutorial_index
That is a link to the monster hunt tutorial, full code for making your game. Idealy, it's a FPS, but can easily be modified to include RPG elements.
My object won't texture?!?!?:
Make sure you've wrapped your model correctly. Make sure you've loaded the correct media. Make sure you've mapped your character the right direction.Make sure there's no mistakes in your code.
etc...
Menus/health bars/skyboxes - see my codebase entries.
http://darkbasic.thegamecreators.com/?m=codebase_list&c=&l=&p=&a=d8f930f085b3181353d68ff08886b657
Hopefully, this will get an F.A.Q started.
(btw, please correct any wrong info. I may have given in the rush to type this, or in my codebase entries.)
A book? I hate book. Book is stupid.