@Nobelix, based on your posts on this site, you seem to be a Linux user. Unity does not officially support Linux, so unless you want to jump back to Windows/Mac, I suggest you embrace the awesomeness that is Godot!!
That being said, using anything other than Godot defeats the purpose of the game jam. ("The main purpose of this jam is to have fun together as a community of Godot users.") Perhaps the organizers should put in an explicit rule stating that games must be created using Godot.