It should be on-topic.
There are several types of games, and each genre as distinct features. First Person Shooters are based on a First Person Gameplay, involving shooting some kind of projectile. Call of Duty? Yes. Link's Crossbow Training? Yes. Both are FPS.
Now what if I ask, are there any games in the Zelda franchise that are also FPSs, the answer to that question would be indeed off-topic, as it would be asking to identify a game. Link's Crowssbow Training to be exact.
But what if I asked if any there's any game who has attempted to be a first person shooter, but while using a medieval weapon? Would that be on topic? That's what this discussion is about.
I think it's on topic because
Game mechanics and terminology
are on topic.
Therefore, should a question regarding whether X is an RPG or an FPS ; or a question regarding whether if there's a game in y genre should be on topic - Do not confuse this as having an answer dictating that games should be given in a list, where every answer is equally valid. No. It's a simple yes or no question, who can be backed up by an example, preferably something that is generally known in order to give a good example:
Are there any games in a Fantasy Medieval Setting with character customization?
Yes, there's Skyrim
Has anyone ever tried to publish a game revolving around Market?
Yes, Rookwood studios with The Guild 2