Here are some questions people have had, if you have a question that isn't answered here feel free to leave a comment!
Q: Can I have a base for my game prior to the jam?
A: You can have a skeleton for a game but can't start production for the actual game, for example you can have a default Ren'Py project ready to work with when the jam starts, but you can't write the actual dialogue present in the visual novel. This applies to RPG Maker games, Godot sample projects, etc. regardless of genre.
Q: What is an MSPA game in this case?
A: A videogame that is clearly set in an existing MSPA property, for the purposes of this jam this includes every story in the homestuck.com site as well as Homestuck: Beyond Canon and Whistles. However note that the jam's theme may not make it possible to naturally feature all of them, but in any case you're still allowed to take aspects from those other MSPAs.
Q: Can we start planning ahead of time?
A: Your planning should be limited to stuff that is typically considered pre-planning, such as picking an engine and figuring out roles with your team and such. It's not recommended you make actual story plans since it may not match the jam's theme.
Q: Are OCs allowed?
A: Very much so!
Q: Can I edit my entry after it's submitted?
A: Once an entry has been submitted and the voting period starts you physically cannot edit the game files but they're unlocked after voting ends, at which point you're free to do with your game as you will.
Q: Does "playable on browser" mean it can be hosted off-platform?
A: Games must be hosted on itch.io and have the ability to be played on browser, you can optionally give download options, but browser is mandatory.
Q: Is Andrew allowed to participate?
A: Yes but is not eligible for the prizes.
Q: Can I use visual assets from MSPA?
A: You can use any visual asset from the comics but it's recommended that you rip them yourself as stuff like bases often go reposted and uncredited.
Q: Can I use official Homestuck music?
A: To use existing tracks you have to ask the individual musician you want to use music from. The artist horizon has allowed for anyone to use their tracks in their games! Motifs are allowed with credits to the original artist.