You could always create a game with HTML/CSS/JavaScript because that’s using skills you already have.
Swift is only for Apple products, but it can be used for websites as well with various frameworks. It’s not useless, but it does have it’s own use case, like every other language.
Android development. This can be done with either Java or Kotlin (another language). It uses the IDE Android Studio.
Unity is a game engine that uses C# as it’s language.
Unreal is also a game engine you could consider because it uses C++. (Fortnite was built with Unreal).
To answer your question, I’d suggest looking into Unreal Engine with C++ or building a web version of a game using HTML/CSS/JavaScript.