SE is meant to be a specific sort of reference. I'll quote our What types of questions should I avoid asking? guidance, which is consistent across the entire SE network:
You should only ask practical, answerable questions based on actual problems that you face.
Most pertinently here: we are not interested in being a reference for endless lists of things. This is mainly because our voting and other feedback systems completely fall apart and become useless when faced with such a situation. Stack Exchange has chosen its niche to excel at, and this necessarily means it sucks at certain things. Lists are one of them.
What's wrong with the question exactly?
If you hadn't guessed it already, it's because it's going to compile a list. Every answer to that question is equally valid. There is no way to determine an objectively good answer, beyond whether that answer merely meets the criteria of being a WWII game or not.
This is primarily because it is not a practical, answerable question based on an actual problem. Let's break it down:
- "Are there WWII RPGs?" is not a problem, just a point of curiousity. It is not practically answerable beyond "yes", and is more an invitation for a person to study further.
- "What are they?" is also not a problem for similar reasons.
- "I want to play something set in World War II, but I don't know what is available! What is there?" is a problem, but as covered in How to deal with questions that just don't understand the scope of the RPG landscape?, there is probably a phenomenal amount of available material. Thus, we will compile a list, and everything is good so long as it meets one single criteria. There is no way to vote for an answer being useful or not useful, other than it's a WWII game or not, and there is no single objectively correct answer, and no answer is better than any other, there are just a lot of them. Our system breaks down. This is why game-rec questions need specific criteria.
- "I want to play something set in World War II. I want the game to involve doing X, Y and Z. A and B are crucial thematic elements and I don't want C. What games are there for me?" Now we're getting somewhere!
That last one can have an objective practical answer. As observers, we can judge whether each recommended system meets the given criteria, and how well it fulfils those criteria, and vote accordingly. Then our system handles it well.
The question just needs to specify some criteria for what it wants out of the game, and then it's golden.