Persist game session data across server restarts

[soceanainn]

Game session data could be persisted in a DB / external cache, but this would incur an additional cost for running this website. As this is currently a personally funded project, cost efficiency is crucial.

One possibility is to persist copies of game session data using client side cookies. While this may be subject to abuse, the rough idea is that:

• each client (player) stores a copy of their game session data as a cookie
• when clients reconnect to the server for an in-progress game that the server has no information on, server requests a 'recovery' from that client
• client returns their copy of the game session data

To stop malicious actors from creating modified game sessions and to ensure the game session data returned by client is the most recent version of data optionally this could be extended so that:

• server issues 'recovery' request to all clients listed in the game session data returned from first client
• once a quorum has been established (a sufficient number / the majority of clients agree on the latest game session data), the server restores the agreed on game session data