as not a game dev i suggest the gnu affero general public license version 3 or later because it guarantees freedom even if the game is run from 'the cloud' (other people's computers)
I favor the Unlicense or CC0. They're compatible with literally everything, no hassle and no fuss.
Some people argue that CC0 is better because it's more rigorous, but it also explicitly excludes any license for patents, and I would argue that shorter licenses that have come up more recently, like Unlicense, take advantage of shorthands created by precedent over time to create a perfectly rigorous license in fewer words.
Of course the problem with releasing your work into the public domain is that most software devs, even in open-source, don't like the public domain, so if you use their tools then that weakens the freedom of your software. The best compromise I've found is to accept their licenses and pass those on in binary but release my source files into the public domain regardless, that way my work remains free.
@mray GPLv3 is mostly fine for games, but you should watch out for its limitations involving stores. GPLv3 does not allow putting your app under DRMs, preventing you from publishing on App Store and probably multiple other stores as well.
Workarounds involve adding an exception clause, making contributors waive their copyright or not accepting contributions at all.
@mray i use MIT for my current project. Might be a mistake but this small engine im making is hopefully a fun toy for many who want to make their own lil fps.
If i evolve the engine further from its current scope i probably will use gpl3.
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