This discussion made me realize something that botherd me for a while.
The tag box with the suggested tags should include certain special tags as suggestions.
Including the platforms. It already includes the genres, even though they are listed as filters on the left side.
That ties in with this issue: the regular search box will actually display the existence of the https://itch.io/games/tag-unreal-engine , when searching https://itch.io/search?q=unreal , but there is https://itch.io/games/made-with-unreal-engine which is not displayed as a result (because it is not in the suggested tag box). It is not even listed in the footer directory - which is hard to reach with endless scroll enabled, btw.