No Unity, Godot, Game Maker, RPG Maker or even WebGL. Just straight up HTML5/CSS/JavaScript using technologies and libraries people usually associate with front-end web development.
The only disadvantage I could imagine with this stack would be that making tons of moving graphics and physics simulations can be difficult to pull off. Depending on this year's theme, we could make an adventure game (think Sierra games or Snatcher by Hideo Kojima) or a strategy game (clicker games, 4X, city builder).
I'm a full-stack developer by profession and have built things for the web for the past 5 years. Here's my GitHub profile. If you're more of a visual person, check out this little interactive website thing I made a while ago.
If you want to join me creating something for the jam, let me know! Artists, and developers – doesn't matter, as long as you're a nice person.