If you make a game engine, would it need to be made during the game jam like assets?

What game engine would you use?

I build a game engine from scratch. Why? Because it’s fun, you get an objectively lighter game (and thus better performance, because it’s tailored to your game), you can support whichever platforms you want, you can code in whichever language you want and in whichever style you want, and we have plenty of time for this jam anyway. Besides, apart from Godot, there is no readily available engine that can be developed with on OpenBSD, and absolutely none of them can compile the game itself for it.

And yes, make the engine during the jam. As I said, we have plenty of time, and building an engine isn’t as scary as it sounds like!

This jam doesn't specify it, but many jams allow you to make some base code beforehand and re-use basic utility code, i.e., a game engine. Just as long as you don't make the game itself before the jam starts. If I make a game it'll be with this framework: https://github.com/morph-games/owls16

i would assume game engines are allowed as most people making games use an engine or framework of some kind. i doubt there is any problem with making your own though. as long as you follow the rule of not making any assets (ie. graphics, sound, music, gameplay code) of your game before the jam starts.