Doesn't that contradict it being open source? Open source implies that it can be modified and redistributed. If you want the developers to maintain all rights, you should change the phrasing from "all submissions must be open source and hosted on GitHub" to "all submissions must have their source code publicly accessible."
I think it’s worth having the rules say “source available” or just “the source code must be published on GitHub” if that’s what you mean, because “open source” does imply an actual open source license to many programmers. Especially since right now the rules emphasize being open source and being hosted on GitHub as two separate things
Same thing for the rules about assets - there’s a big difference between assets that are “free and open source” and assets that are simply free to view/use. For me personally the former implies that e.g. art assets have to be Creative Commons licensed (or similar).
I think we understand the spirit of what acerola is going for here. it's pretty clear lol. the reason I made this thread was because i want to be able to sell the game later if I like my entry and sometimes "contests" (not most game jams), gain some kind of rights over entries submitted. so it'd be nice to have that specified that's all.