Yep, any engine.
Will they be judged altogether, or by engine grouping? I ask mostly because I intend to submit in RM, but recognize the very clear superiority in graphic and mechanical capability for Unreal, or Unity. I suppose a great project is great regardless of engine, but just thought I'd ask.
They will be judged together. To be honest, since I was a judge the last time we did any engine for the contest, I wouldn't be too concerned about it. Some of the best games in the contest were still RPG Maker games.
Powerpoint? Notepad?MS Paint?