Hey there, I use DAZ3D to create the images in the game, it's a 3D modelling and rendering suite. It has quite a learning curve, but there are many tutorials around.
I use Iray (the rendering engine) to get the look in the game. SickleYield has some nice tutorials: https://www.deviantart.com/sickleyield/journal/SickleYield-Tutorial-And-FAQ-Inde... This is a nice introduction: https://www.deviantart.com/sickleyield/journal/Brand-New-To-Daz-Studio-FAQ-64545...