Simply put, a sort of re-implementation of what the game directory can do: via whatever database or catalogue is available, (e.g. Giant Bomb or Twitch’s own), provide an on-player panel showing information about the game the channel is set to. Could provide box cover, screenshot, brief synopsis, dates and companies, so on.
It could be implemented as a panel but I feel it would be better served by being right on top of the game feed itself–mouse over the player, get a quick overview and perhaps links to external information or storefronts.