Why do these questions get closed?
We close these questions because they're list questions, which we declared as off topic in 2010. List questions tend to break our Q&A format: there's no single objectively correct answer, and no answer is better or worse than any other, so long as it simply meets the criteria provided. Our voting and accepted answer systems become irrelevant.
If you have a real, answerable question based on an actual problem you face, and your game recommendation fits our game rec rules, you're welcome to ask it, but if you just want a theoretically endless list of stuff, this isn't the place to ask for it.
We demand narrow criteria from game rec questions because that's what it takes to make our system useful and relevant again: a sufficiently narrow question will cover only a small portion of the RPG landscape, and we'll actually be able to recommend an RPG that's probably objectively the best one for your purposes.
This is sometimes tricky though, and criteria you think are narrow might cover 90% of RPGs ever. In those cases, we need to put your question on hold and work with you to refine your criteria.
What do I do if I don't have narrower criteria?
Chances are, you do have them.
If you want to play in a World War II setting, for instance, you probably have an opinion on whether your game should focus on soldiers, espionage, strumpets, office workers, doctors, detectives, or so on during the period. You'll also likely have a preference on whether you want to focus on tactical action, personal drama, or other stuff. So think about those things, and tell us what in particular you want to do.
But I really don't have any preferences like that! I'll work it out myself, just give me stuff to browse through.
If this is the case, it sounds like you're here too soon. We are not here to produce a list of dozens or hundreds of arbitrary things for you to browse through: it breaks our format, and amounts to menial grunt work, which isn't fun. You need to do some work yourself to figure out those criteria before you come here.
Do your browsing on RPG Geek (which has thousands of RPGs catalogued) to work out what's available first, or on Google or at your friendly local gaming store - compilations have already been gathered for you! Think about what kind of game you'd want to run exactly, and if you're at a loss due to a sheer number of options, pick something appealing.
Once you have your criteria, then ask us what game or adventure would best support you doing that kind of thing. When you do that, we can weigh what we know and our answers to find something that best fits your requirements, and our voting and accepted answer systems are meaningful again, and it ceases to be a list question.