You likely have several questions about all this. I will do my best to answer you here.
(If you have a question that isn't answered here, try the Overseer Wiki FAQ)

Q: Who are you?
A:You may refer to me as The Overseer.

Q: What's going on here?
A: The short answer is that I am attempting to create and expand a new multiverse, distinct from the suffering and tragedy that mark the one I left.

Q: How?
A: By completing sessions and populating the new multiverse with as many realities as possible. Although I alone cannot bring an entire multiverse into existence, I intend to provide the means for you, the players, to do so through your combined efforts. I have modified the universe propagation tool, known as SBURB to many of you, but my efforts have resulted in a few minor setbacks.

Q: Setbacks?
A: Part of the rebuild involves resetting the universal processes that allow for what you interface with as alchemy, the process by which all items can be created. This means that most of the combinations don't actually map to anything in the new multiverse you are now a part of. I will be creating every code by hand with the assistance of the players: you will submit suggestions for both specific codes and items that need to be in the system somewhere and I will bind the codes to the items, allowing their alchemization. To get started with alchemy, you will need to access the catalogue for items to begin experimenting with.

Q: Is this thing even finished?
A: Another setback, I suppose. While I have provided the basic means for you to finish sessions, I have been working on building upon mechanics to aid you along your way. The current system only allows for basic interactions, however, more complex methods to progress through a session are coming in the future. Please keep in mind that reverse engineering a complex multidimensional tool such as SBURB takes time; have patience.

Q: What's the deal with sessions?
A: A session may be created at any time. Any player who enters their Medium must provide an existing session name and the session's corresponding password, placing them as a player of that session.