Examples?

Has someone done this in the past, and you think I would improve it with two of them? Link/explain how they did it.

Potential Title

Try make sure the title peaks the viewers interest and is highly clickable. e.g. MAX LEVEL in Fortnite vs We hit level 225

Why would a viewer click on this video?

A video must appeal to a wide range of viewers and should be unique. A video such as "first chest challenge" has been done by everyone, and hence people won't click unless it has a significant twist. A good video will appeal when the viewer hasn't seen that idea done before, and they can't predict the outcome from the title/thumbnail.

Why would the viewer watch the entire video

A good video idea gives people a reason to watch the entire thing - either through entertainment value, being new and unique or a good hook.

Does the video evolve over time and how?

Not required, however it helps. Some challenges don't give the viewer a reason to continue watching. A good challenge gives a person to watch the whole video. i.e. one chest challenge - viewer can see the loot initially and skim to the end which is bad, whereas a kill race has an ever-changing leaderboard, or the challenge involves doing something over and over where each thing is better than the last.