I'm only using Unreal as a search result example to see if I am successfully displaying all games on sale (I don't need to search for Unreal, I already know I'm going to buy it). I'm wondering if I am just not using the site correctly to show all sales (including, for example, Unreal), or if this is some kind of bug.

Thanks to anyone who might be able to help me.

I found it in sales list, here what you need to do:

1. In sales page, change filter to "package only" at top right (get steamdb extension just incase)
2. Some deal will be hidden, so press "show xxx other deals" in the list
3. Ctrl + f for word "unreal" and you will find it.

Using top right search function seem to bring up all games with "unreal" in the description (and sometimes word with "unrel" also brought up)