There isn't much to be said.
It's still the same as ever when Synbios was originally created with my own third rule.
1. No porn.
There are better sites for that.
2. No piracy stuff.
There are better sites for that too. Emulation and modding is fine though, see rule 3.
3. Use common sense.
Seriously. If you have to ask yourself "Should I post my plan to shoot up a place here?" the answer is probably "No.". Seriously, the server is located in the U.S. so the respective laws apply. Use some common sense.