there are just off the top of my head, I'm sure others can extend it, you can also ask in the RP community discord here: https://discord.gg/YB4bCfx
your basic rules are being polite and keeping discussions civil, no stealing ship, keeping things on topic etc
However the more "Lore" rules if you will are things such as no starting with huge empires, i think the current acceptable starting size is something like 25 star systems, this also goes for the #of ships, obviously a new empire starting out should not have 20 battleships, 100 cruisers, and 200000 fighters, I'm not sure what the acceptable number for all are though but personally i think the largest a starting empire should have is at most a destroyer. When it comes to races most people obviously go with humans and will have super solders, however sometimes people will make custom ones, this is ok and encouraged to a degree as long as their not broken where there immune to anything but cretin things, there should be a believable balance between strengths and weaknesses. there's also things like the only way you can develop your technologies is by being involved in events. Wars are obviously conducted on posts, i don't know much from how exactly they are conducted but but I'm sure people on the community discord can explain that. however usual if things become toxic or theirs a issue the community will decide what happens, rather that be one side is BS'ing their attacks, or if both sides are getting toxic.