To find out what stairs you can currently challenge someone in, first go to the Main Stairs Page, then click on "Show your stairs only" link. The ones in BOLD are ones you can make a challenge in.
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Is there anything to prevent the person at the top of the stairs to not challenge. No one can challenge him until they reach the same height, right? So they can just chill at the top until someone gets to the same stair and challenges them (if they have an open challenging slot of course)
(hide) If you click on a person's name and then click Finished games you will have a list of games that have been completed, then click on the name of the game to get a summary of all of these games, then click on the name of the game again and you will have a game to view and analyze. (Servant) (show all tips)