Using github pages as development blog

Question

Can I use github pages for free hosting of a development blog about my game, even if:

1. the game itself is not hosted on github, not even in a private repository,
2. the blog would contain posts not related to software development, but still related to the game design or behind the scenes ideas and discussion,
3. after the release of the game, the blog would point to a store where the game can be purchased (an ad)?

Answer 1

Yes, you can host a dev blog - this is covered directly in the GitHub Pages documentation:

With GitHub Pages, you can host project blogs, documentation, resumes, portfolios, or any other static content you'd like.

However, they retain the right to remove content:

We have the right to refuse or remove any User-Generated Content that, in our sole discretion, violates any laws or GitHub terms or policies.

And they have restrictions on advertising:

While we understand that you may want to promote your Content by posting supporters' names or logos in your Account, the primary focus of the Content posted in or through your Account to the Service should not be advertising or promotional marketing. This includes Content posted in or through Pages, Packages, repositories, and all other parts of the Service. You may include static images, links, and promotional text in the README documents or project description sections associated with your Account, but they must be related to the project you are hosting on GitHub.

You'll need to read their terms of use carefully and consider how well they align with your plans and intent. Having backups for anything important is generally good advise & more so considering they can pull your content at their sole discretion. As mentioned in the comments, there are probably better alternatives.