It's not very hard to create new characters in DAZ once you get some of the basics down. I usually first decide what I want the character to look like (cute, short, curvy, and redhead?) or maybe I'll know an actress that I like the look of.
Then I'll pick a Daz Character that gets me close to what I want. I'm not sure how familiar you are with the DAZ models yet but you have the figure type such as Genesis 3 or Genesis 8... Then there are characters you can use based on those figure types. These character usually have a Name such as "Emmanuelle for Genesis 8 Female"
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This is the character I used to create the girl in my avatar image. As you can see they are similar but not identical. I then went to the Parameters tab for the character and started adjusting her body and face so she fit closer to what I wanted.
There are tons of characters available for purchase at sites like Daz3d or Renderosity - as well as other sources that are more on the "free" side.
You don't have to customize them of course but once you get comfortable doing that it's too tempting not to try to improve them.
What I find to more of a problem is locating a hair product I'm happy with. Ideally it would not only look good but offer a number of morphs so you can adjust it for different shots, such as having the wind blow it or if they are bending over having it fall correctly.
If you are doing an adult game you most likely will want to use 3rd party genitals which looks great and give you a lot of control. I've been using, and very happy with Golden Palace (female) and Dicktator (male) which are available at Renerotica.com. This site will have a ton of your adult themed things such as poses, body parts, 'squirting fluids', and sex toys.
I hope that helps out some. Once you play around creating a few characters it becomes easier and faster.