Since itch has free tagging, 70+ games already did have that tag.
For single word searches you might want to consider to insert some short blurb anyways, even especially if there are no suggested tags as a result. It could read similar to "Missing something? Maybe try freestyle tag filtering instead (show tag filter box here)". There are many tags that are used and have many items, but are not in the suggested list.
And that tags are freestyle is not really advertised prominently. I remember a heated discussion where I even was called a liar, for claiming that tags are freely choosable and was quoted the then 14 pages of "all" tags.