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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plaintiger: You have right. If you click and go to Stairs from main menu it is okey (bold), but you choose to go to the Stairs from 'Profile' it does not show bold in it! This is a bug
(hide) If you want to find out more about some games you can check the links section and see if you find any interesting links there. (pauloaguia) (show all tips)