Suggestion: private games
Today I thought about the possibilities to have small competitions in Geoguessr, while making it (at least) very hard to cheat. Right now such preventions are not really necessary, but I could imagine it being handy.
My idea is for someone to be able to create a private challenge. As in: he creates a challenge, and he can invite other mailadresses (his friends/competitors) to that game. Instead of everyone being able to join in on the game if you got the URL, only the accounts associated with these specific mailaddresses are able to play the game.
Further thoughs why this could be a handy addition: if you could create a group of friends who always play games together, the other players in that group could get an email notification when a new challenge is added to that group. It might be handy to choose that either the admin only, or just everyone, can add challenges to the group.
This would especially be nice when you would incorporate stats for all players of a challenge, instead of only the first two.
These are just thoughts, maybe I haven't thought them through enough, but hopefully they might spark some ideas on your side as well. :-)