I've also had a quick look and yes, this appears to be a game mode rather than a game and this tag in its current use is ambiguous and inconsistently applied. This tag in my opinion falls under the meta tags section and possibly even with differing meanings in different games of the tag cleanup we did a few years ago and should be removed.
I think the tag is just fine as it is. The excerpt mentions that the tag should be used
For questions that ask what a gaming-specific term means.
Nothing about it mentions labelling a gaming-specific thing with a name. Furthermore, the tag's full info mentions that
It is not appropriate for repository style questions that seek to span the terminology ...
I personally think that we should rename them to be starcraft-zerg, starcraft-protoss, and starcraft-terran. The reason being is that all other tags that have subcategories in them, such as Minecraft, TF2, and Skyrim all follow this naming convention, so we should continue this convention to be consistent.
I don't think we need to change it to use ...