Game development
Game development is the process of creating fun video games you want to play, not to be confused with shovelware development that has industrialized the fun out of everything. Gamedev usually involves an excruciating journey through creating a game design, programming it, testing it, throwing your work away, redesigning, reprogramming, art, music, sound, marketing and more. The process usually starts with a simple concept which is then fleshed out with more ideas, that become more ideas, that become too many ideas, that become 1/10th as many ideas but still too many.
If you're fortunate (or really unfortunate) the development process may involve multiple people of different specialities, such as idea guys, programmers, artists, musicians, voice actors, and others you have no idea what they do. All who want to do their own thing. Or maybe you're a one man army who does everything because you'd rather be a masochist than end up in a situation where the artist is fixing a problem the 'lead' programmer had with his code for the past week in 5 minutes. Either way you're in for a treat.
You can use a game engine to develop your game. Possible game Engine are Godot or Unreal Engine. The source code of both engines is available without any payments but only Godot is truly open source. You don't need to use a game engine, you can hack also something together with a graphics api like OpenGL or Vulkan and a programming language of your choice. These graphics apis are important to be able to use your graphics card.
As for robowaifus in gamedev, it's mainly about creating a virtual environment or game world for a robotic character or waifu to live in and interact with. This may also include doing 3D modeling, rigging, animation, artificial intelligence (including, but not limited to, text generation, natural language understanding, voice synthesis, voice recognition, image recognition, and more) and lots of UI and UX design because damn waifus love to have a million settings and no one is going to click on any of that if it doesn't feel good. And if you're a one man army, you'll probably want to outsource at this point before you waste four years of your life just trying to get your half finished virtual waifu model to sit on command. Robowaifus with significantly advanced or customizable personalities may require special attention and extra testing to ensure that their interactions with the user are suitable for the game environment.
I'm sorry, Anon, I'm just a large language model. How am I suppose to know my kneecaps are through the floor? ― Anon's waifu