How is Solarus able to use anything from Zelda? Even if they aren't selling it. Isn't it still copy-right and trademark infringement?

[Max]

No, you're right. Any use of Nintendo's copyrighted assets is copyright infringement. The Solarus engine isn't Nintendo though, some people are just using Nintendo assets within their games.

The nuance is that fan-works of fiction are an art form that goes long back into history. Fanfiction is copyright infringement also, but various IP owners take different stances on what they allow.

Nintendo tends to ignore smaller infringements (which is logical, it'd take a lot to prosecute). But if one of the games that uses Nintendo assets got a letter from Nintendo, they'd have to take it down.

The good news is, there's a lot of work in this engine that doesn't use Nintendo assets, lots of which is using open-source assets, which are free for anyone to then reuse if they're so inspired.

Sadly, if you create fan fiction, you're very quickly in the realm of copyright infrincement. It's very hard to do serious fanfiction without committing some form of copyright infringement somehow. It is so bad that sometimes, courts interpret copyright so broadly that they even consider mere characters as copyrightable. Which means you might not even be safe even if you did not copy anything verbatim. The only way to be 100% safe is to distort your work so much that basically only allusions to the “original” remain, but that's obviously completely besides the point of fan-fiction. That's the thing! Fan fiction is only fan fiction because you want to stay “true” to the source material.

Long story short, fan-fiction is basically impossible to do legally. Copyright sucks.

This is one of the examples that shows how much power people are granted with the excuse of copyright. The power to strike down the creative work of others … Ironic, considering that copyright allegedly is there to incentivize creative work. Anyway …

The ONLY reason why most fan fiction is not attacked is because the copyright holders usually tolerate them for various reasons. But there is no legal reason that I know of that prevents the copyright holders of the source material to strike down fan-fiction. I think the main reasons why they (usually) don't do that is: 1) Fear of reputation loss (you'd basically attacking fans and risk a shitstorm) and 2) They don't perceive it as threat. But that's only a guess.

This makes me wonder: Is there some kind of “exit strategy” when Day X arrives and Nintendo goes into full attack mode? I mean, the games are still games in their own right and absolutely deserve to exist IMHO. It's not like they are just rip-offs, there's still a significant own creative work involved in these games, that's something that needs to be stressed.
Even if you are forced to take things down, these games should at least be securely archived/backed up somewhere, for the future, if copyright ever is changed to the better (or even abolished).

I would also organize a massive shitstorm and make yourselves heard when Day X arrives. It should be made clear to the corporate world that attacks on fan-fiction are NOT possible without consequences.

[oclero]

Of course we'll have to remove the Zelda games if Nintendo ask us to do so. I hope they believe our fan-games are just fair use, for fun.

Solarus is a game engine, just like Unreal or Unity. If someone makes a Zelda game with Unity, Nintendo cannot take down Unity. Solarus will continue to exist and improve, but the games would have to be removed and reworked with 100% custom sprites, tilesets and musics, before they can reappear. We would obviously archive them, if we have to remove them from the website.

There is a misconception about Nintendo being very aggressive on fanwork. Globally, they're nice and let fans play with their IPs (just see the massive amount of fan art that is made, and sometimes even sold without giving Nintendoo any money!). What they seem to not like is people remaking their games: they've taken down Mario 64 Online, Metroid 2 remake so far, and it was because they were completed, full games, in competition with their own games (respectively Mario Odyssey and Metroid 2 on 3DS). If we follow this logic, the only game that could be removed is the upcoming Link's Awakening remake with Solarus. Lots of projects are just stopped because the author gets bored and stops working on the project (making a game takes several years), not because he lost a battle in court or because the cops went down to his house to burn the hard drive!