New topic: Endless Sky

[TheGiraffe3]

Please confirm this pull request meets the following requirements:

• I followed the contributing guidelines: https://github.com/github/explore/blob/main/CONTRIBUTING.md.
• I am not the sole author or employee of a company who created either the topic I am modifying/adding or the collection entry I am modifying/adding.

Which change are you proposing?

• Curating a new topic or collection

Curating a new topic or collection

• I've formatted my changes as a new folder directory, named for the topic or collection as it appears in the URL on GitHub (https://github.com/topics/endless-sky
• My folder contains a *.png image (if applicable) and index.md
• All required fields in my index.md conform to the Style Guide and API docs: https://github.com/github/explore/tree/main/docs

This topic should be curated because: Endless Sky is a large game with lots of players.

[tomthorogood]

@TheGiraffe3 sorry that the checks are giving you trouble. Can you put endless-sky.png back? We can override the checks if they are giving you a false negative.

[TheGiraffe3]

@tomthorogood thanks for the help! I got it to work by compressing the file, and the checks are passing now.