Let me explain a bit
The program itself doesn't necessarily matter, there are several options that one could run on their own GPU to generate images
I personally use Forge WebUI, can't say for sure what each game dev is using
The art style is the more important part, and that consists of 3 things in essence
1. The checkpoint
2. The Loras and their strengths
3. Style specific prompts
It's the combination of the above 3 that define the art style for each game
The thing is, devs usually don't mention much about this, even when asked
In the case of this game, BCG has given some information in the fan art thread
Start from the post below, and check through the following pages, BCG gives quite a bit of info
https://f95zone.to/threads/moonripple-lake-bcg-fan-art.225747/post-17144514