There is an Inform game in public domain. I made a translation in another language with few code modifications. Now I want to release it under Apache License 2.0. Is it legally OK? How should I give copyright notes? Can I put license text in game or it should be in a separate file (LICENSE)?
Or is it better to apply another license? I need a permissive license, that allows distribution without source code and that requires state changes notes in derivative works. I think about Attribution-ShareAlike 4.0 International, but it recommends against using Creative Commons licenses for software.
I’m not a lawyer, but usually a straight translation does not entitle the translator a whole new copyright. The copyright still belongs to the original creator, or in case of public domain, remains as public domain. Regardless, you still need to credit the original author as the author of the work.
What is the game, anyway? Did you contact the author so that he/she can distribute the translation along with the original?
I believe you do have a separate copyright as a translator (other translations can’t copy yours) and legal rights to modify and relicense a public domain work. But there’s no clean way to do this.
Let’s take as a premise that the work is public domain in US, code and text. That doesn’t mean it’s public domain in your country, because even the concept of the public domain is different across the world. The point is not that the original author will sue you, it’s that your claim on this work can be disputed, especially if you didn’t contact the author.
You do have 100% rights on the text. What is the possible copyleft use here? A new Inform 6 author writing a fanfic? Someone translating your translation instead of original? Someone publishing your game commercially? You did use a PD work and still credited the author.
You say you made some code modifications. See, it becomes harder to enforce any copyright if 90% of your source code is public domain and the stuff you can claim as yours is a code snippet of 100 lines or so.
Inform source code is a learning tool. New authors copy this stuff. If you want to package your code for sharing, just make it a library.
I believe this is similar to the situation where, say “Toccata and Fugue in D Minor” by Bach is public domain, but a recorded performance by a keyboardist can be under copyright. One can use the notes and melodies of the music for free, but not a copyrighted recording of it.
Depending on what the OP wants, and since they are not technically copyrighting software but the specific written translation, I believe they could use a CC-BY-SA and specify it’s for the translated prose only and not any underlying software or code.
There are indeed separate copyrights for music recordings and musical scores. If I recorded myself singing Gaudeamus itur, I could claim copyright on the recording but not the score (notes/lyrics). Unless I translated the lyrics into English, in which case, I could. Unless I used Google Translate to do it, in which case, I couldn’t.
If anyone needs the legal details on what can and cannot be considered public domain and what you can do with those public domain items, I suggest you start here.