I think they meant "casual" in a conventional sense as "easy to get into" as they talk about "simplifying learning curve". So opposite of it is "hard to get int

I think they meant "casual" in a conventional sense as "easy to get into" as they talk about "simplifying learning curve". So opposite of it is "hard to get into", and "immersive and realistic" is one kind of such games, but not the only one.