I'll be starting tagging games that are unique to any given platform soon with noports or similar (if I can think of a better one before starting). This would be for games that don't have versions or ports on any other platform, though mostly cases with desktop computers and home consoles, skipping handhelds and such. People considering on getting new platforms are usually the ones most interested in these (as in, what games does this platform have that the others don't).
Games unique to a platform
No ports holds these now.
Wouldn't this be implied by a game not having "version of" relations? Then queries for platform-exclusive titles could be supported from the search (a checkbox to find platform-exclusive titles that eliminates entries from the results if they have any 'version of' relations). Otherwise this tag could grow rampant.
Yes, but lack of such relations may be simply that no editor has added those relations yet either. Also, it would need to cover port of relations as well. There's good sides and bad sides for both solutions. The tag is better in that it guarantees that the game has been at least at some point reviewed to be unique to a platform, unlike the automated one which can only say "this is probably unique to the platform".
I see your point. Assuming that people are more likely to search for platform-exclusive titles than multi-platform titles, which seems likely, a tag is the "safer" solution. Also, I see it makes the tag's page particularly useful for finding a certain platform's exclusives.