Mashup games are always fun. Those built upon FourSquare have an extra layer of enjoyment, because they're tied to the real world. In the case of City Warfare, players use various water weaponry to soak other FourSquare users.
As messaging apps scramble to out-feature the competition, Telegram has launched a gaming platform within its Bot API. Most messaging apps have now included bot capabilities within their apps, but Telegram has upped its game with the ability to build games within the messaging app.