How about free forever assets in Unreal Marketplace and assets that can be used only with Unreal Engine? And Quixel Megascans? Can I use it?
Viewing post in Free Asset Rule
You can use free forever assets even if they're restricted to the engine you're working with.
From what I can tell regarding Quixel Megascans specifically (and this is their TOS not this gamejam's rules), you can use their free assets non-commercially so it should be fine for this jam as long as you aren't selling the game you make.
I don't think that's an issue for Quixel. Unreal Engine TOS seems to overrule Quixel TOS per their arrangement with Epic according to this.
https://www.reddit.com/r/gamedev/comments/rhfvxg/am_i_able_to_use_assets_from_th...