All you have to do, is make it happen.
This is not some point-and-click POOF you magically have the game of your dreams thing...
...you gotta work at it to get the results you dream of.
It's all entirely possible, but you're not going to produce 100 hours worth of game-play content in one night of clicking a few buttons.
Your example of the game FATE is a nice looking game.
How many programmers and artists do you think it took to create that game and get it online for you to play?
And with a crew of professionals working on it every day, how many months do you think it took them to produce the game you see now?
PlatinumArts Sandbox is a wonderful software for producing great 3D games. BUT... it is not going to happen overnight, and it is not going to just magically appear before your eyes all of its own.
You'll need to learn how to create 3d Models of objects and characters, learn how to rig and animate the characters. You'll need to learn how to produce good graphics for skins and textures. And you'll need to learn how to write the scripting language that makes it all come together.
None of this is going to happen with a few clicks of a mouse-button. It takes a lot of time, patience, determination, and dedication to produce truly awesome games. And even then, it also takes talent to make it all look beautiful.
Do you have what it takes kid?
If so, make it happen.
The tools are available. PAS, Blender, Gimp, Notepad++, along with music and other assets already available in the PAS package.
All free for the using. Make it happen.
That's how it's done man. Nobody will make your dreams come true for you... That, my friend, is your own destiny to fulfill.