Nintendo was able to sue palworld using a patent that didn't exist before palworlds release. It's not right, but they can do whatever they want regardless of what the law says.
People say this, but I believe it is mostly technically untrue. It'd be a relatively easy argument to say that a downloaded ROM that isn't exactly the digital copy YOU purchased with a license would be seen as not legal.
However some people talk about literally ripping the game off the physical device themselves, hence copying their own copy of it. Now you are in grey territory of making copies of copyrighted materials, and in the case of more modern games like the last decade, they almost assuredly have language that specifies you don't actually own the code and all that.
All I'm saying is be careful and probably refrain from repeating the fallacy that owning a game makes emulation of it legal, because that implies having the ROM is legal and that's doubtful.
Each game needs to have a custom profile created to render in 3D. From the linked article:
3dSen is an emulator that lets you play 2D NES games in 3D. Its programmers have to create a custom profile for it to work its magic on each game, which means there are currently 100 supported games, including Contra, Super Mario Bros, Batman, Castlevania, Bubble Bobble, and Gradius.
Still, being able to argue they're not for profit is what typically has protected emulators from being sued to oblivion (and with Nintendo, even that's risky)...