Also I suggest making it really easy to invite someone else to play with you by sending them a link. That's more complex though.
Also since you already have a spectator mode, it'd be cool if people see an active game when they go to the home page, like lichess.org. That might be even harder to do that invite links.
A recent web game on HN ("Pounce") did the first part well: https://news.ycombinator.com/item?id=31073332
Also I suggest making it really easy to invite someone else to play with you by sending them a link. That's more complex though.
Also since you already have a spectator mode, it'd be cool if people see an active game when they go to the home page, like lichess.org. That might be even harder to do that invite links.
Nice that you can share the result of a game! http://www.battle-of-flags.com/match/index/695