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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pauloaguia: I was talking about how people are saying things about being informed when there are challenges available, without having to go to that list and check.
(hide) When moving in a game you can choose which one will show up next by selecting the appropriate option in the list next to the submit button. (pauloaguia) (show all tips)