Code cleanup obviously to prep the way for new features.
Custom piece addition. Will want to rethink this somewhat so pieces can be black or white and maybe are added simultaneously.
Board size alterations (via buttons that appear on the edges of the board)
Allow the creation of new games
Save state copying
Version 2 (forked)
Hardlinked players + spectator rather than the awkward POV / free sandbox thing. Makes sense to split the project here so the sandbox variant still exists.
Message stickying
Custom rule sets would be nice -- would pave the way for making this a full fairy chess engine.
This in turn would lead to game style copying like tamerlane chess or w/e.
Obviously, integrate this back into the hub in some useful way.