Nintendo's biggest strength is probably how well their products market to kids and younger people. Market to kids well and they'll stay loyal throughout their whole life.

Unity, and Epic's Unreal Engine, is more than just a game engine. I think this is what most people not in the industry misunderstood (kinda like how most people think NVidia is just GPU manufacturer, and Amazon is just online marketplace). These tools are gaining more usage in other fields (UE is still dominating but Unity is the next alternative). Unity is definitely a good investment, though it might be overpricedat the moment, but what isn't in the current market. And when or if Epic ever goes public, even if Fortnite to die out, it will still be a good investment IMO.

Similarly, Roblox caters towards younger generation AND creators. I personally don't know how long can they stay relevant, but it's a very strong one.

A little bit off topic, for those who are interested tolearn more about what these companies do besides what most people know about from their general news outlet, I'd suggest subscribing to their developer newsletter. Some of the news might be over your head if you're not in the industry or just not interested at all, but some of it are pretty standard. These news could be useful to gain more insights for fundamental investing strategy, and to stay ahead of the usual news outlet, good luck!