Challenges
Challenges is a place to bet against another player and let something other than luck decide it.
Two kinds, and they are the same thing wearing different gear. A street race is settled by what you drive. A straightener is settled by what you brought. Put a stake up, and whoever wins takes the pot.
The part worth understanding
Being better equipped helps, and it is not the whole story. The gap between your gear and theirs moves the odds, but it stops moving at 70%. The best-equipped account on the server still loses three out of ten to somebody who started last week.
That is on purpose. A bet the underdog can never win is a bet nobody takes, and then there is nothing to do on the page at all.
Money
Your stake leaves your pocket the moment you put the challenge up — not when somebody accepts it. That way nothing on the board is an offer its poster can no longer honour.
A slice of the pot burns. The winner does not take both stakes; they take both stakes less the house's cut. Two people betting at each other all evening will both end up poorer, which is the intended shape of it.
If nobody takes your challenge, it lapses after a day and your stake comes back on its own. You can also withdraw it at any time before somebody accepts.
Aiming one at somebody
Leave the name blank and anybody can take it. Put a name in and only they can — they will be told, and it will be waiting for them whenever they next look.