Thank you for your question, your game looks very professional :)
I think in the spirit of the jam we can keep it to people who make their game during the jam period. Maybe not a lot of people will join, but that's okay, sometimes small jams are good so people can get feedback and feel less pressure. I think it will be fun for anybody who wants to join to try making a game in 3 weeks. Sometimes people also only join when they are about to submit, which is near the end of July.
Have a great day :)