Is using another game engine allowed?
From the FAQ and Rules section on the jam page:
Q: "Do I have to use RPG Maker for my game?"
A: "Entries made in any version of RPG Maker are preferred. If you use RPG Maker to make your game, then you can just make whatever you want. There have been Visual Novels, stray-cat-simulators and more made for this particular game jam."
"It's also possible to use other game engines, but if you don't use RPG Maker for your game, then additional limitations apply. In that case, you are required to make some kind of top-down JRPG-style game in order for your game submission to be accepted."