The 1979 classic game Lemonade Stand as a Facebook bot.
From the announcement:
Those of you who are a bit more…senior…may remember playing the classic Lemonade Stand “business simulator” game on the Apple II. For me personally, it holds a special nostalgia as one of the first computer games I ever played.
Well, we dug up the source code and ported Lemonade Stand to Facebook Messenger. While we made some small changes to the UI for it to work on messenger, we kept all the original game settings and equations. If you’ve played Lemonade Stand before, you can now relive the days of your youth! If you’ve never played Lemonade Stand, you’re in for a retro treat.