I actually think that we've got a good framework just by looking at our four most popular questions:
Looking for solo (one person) RPGs - do they exist?Looking for solo (one person) RPGs - do they exist?
Are there any good tabletop RPGs for young beginning players?Are there any good tabletop RPGs for young beginning players?
What games are out there that could be played in a single night, with no prep?What games are out there that could be played in a single night, with no prep?
1 GM and 1 Player games and game systems?1 GM and 1 Player games and game systems?
In this case, we see that there are some pretty simple guidelines here. They look at a specific audience or purpose.
Asking "What game should I buy" is obviously meaningless, without providing an idea of what we're looking for. What can be clearly seen from this is that there are a few core criteria:
- Specific audience. We either see a number of players (one person, one person and one GM, young people) or a specific condition (people playing for just a single night).
- Actually not subjective. Only one of these mentions "good". Others are just asking "does something exist within these criteria". Even then, we see objective criteria; "less bloody and dark".
- Very general. Any of these questions has many acceptable answers, and possibly has many equally valid options. Some of these options will look nothing like each other. While some will be more positively received, there are not a ton of "invalid" answers.