I think there's really just no good way to do voting. The only people who will realistically and reliably vote are the participants, so we just kind of have to choose it like that. We don't have judges because that's not really what my jams are about. I'm not looking for "the best game." I'm giving reason to make narrative games. You don't get prizes for "winning" the jam. Everyone gets their game played by me on stream. That's not much of a "prize," because I'm just some guy with a degree. If we were to give out real "prizes" for jam entries, we'd have judges, but even then, what do judges know that devs don't? Does it really matter, in the end? Haha.
What these jams are based around are what are called "workshops" in fiction writing school. How workshops operate is everyone writes their story, brings it to class. Every other workshop participant reads the story, comments on it. The creator takes the feedback and goes into the future knowing what they're good at and what they can improve. No one "wins" a workshop.
In the same way that these workshops work on everyone getting their stories read, these jams should work on everyone getting their games played. I can't enforce this, though. If people don't play, then they don't play. It's unfortunate, because that can lead to wonky results, but that's also why I refuse to give out a prize other than "my time," which everyone gets equally haha.