Just a wild guess because I have never played that game but I would assume possibly he used Blender or 3ds Max because the renders don't look like Daz quality
But I do think it it possible in Daz to make that cartoon affect
About the Game engine I would assume RPG Maker MV or Game Maker Studio
He uses RPG Maker MV with several add-on scripts to create a game. His models are TK17 (The Klub 17 - 3D Sexvilla) that is also heavily modded with addons from modsgarden to improve the lighting, poses, models, etc.