From my observation the search has two kinds of results. It does title matching. Then title matching by "relevance". Like boxing will also match box. But it does not match any game that has no "box" in the title.
Let's try fishing. That is also a tag. The new box will suggest fishing as a tag. Note, boxing was not suggested as a tag. It will suggest boring.
The search result will also display fishing as a tag and then all the games it deems currently relevant for fishing, and those are only titles with fish somewhere.
So why was the tag boxing not shown as a search result? Because it is not in the list of featured tags. Or suggested tags. Whatever you want to call them.
But from my testing, it's not only the title, it's also the short description/tagline
I believe that people think this, but can you give an example, where the title has not resemblance to a word, yet you can find it in search? Fishing and Boxing were both negative.
Spamming the title with seo terms is a problem. If I were to implement search algorithms, I would activly punish such titles's relevance, since they are obviously spreading out their relevance.