As we have commented before, the challenges are totally different for every event and are changing the thematic of it, also the difficulty is affected.
Every challenge has a time limit that shouldn't be exhausted because in this case, the scores of this challenge will be 0 for this player.
Also exist a series of rules to follow on the challenge, but is the viewer's responsibility to decide if these rules are respected and can be expressed on the viewer's vote.
The players and the viewers can suggest new challenges that can be introduced or not. This responsibility remains on the Nergame platform.