The 404 page appears when there's a broken link, missing content or the server is down. This might seems something not very important, sometimes even being neglected. But I think every part of the website matters, and this 404 page, is an opportunity for brands to show their personalities.
Most of the pages asked the users to go back to the previous page or go home. But in UX perspective, it might not serve the users goals' and address their frustrations directly. Without making users' loosing their interests on the website, I think a search bar is a good solution to provide the next step for the users.
I really like Space, aliens stuffs so I created this for the Daily UI challenge on Sketch. There's a search bar below so users can search here instead of going back.