I just posted a second answer to my game identification question: Searching for video game like Xevious but with more interesting bosses —the reason being that I discovered that I had combined elements of two completely different games in my question.
I am adding a second, separate answer here, because I have located a different source for one part of what I was asking about in the original question.
is how I explained what I was doing. However, I realized that I did not really have a clear picture of how we should handle questions like this—particularly with respect to closing duplicates.
This Meta question: How to deal with abandoned potential multiple story identifications? tries to address a specific issue (involving what to do "if the question is abandoned") that could arise when somebody conflates material from two or more stories in a single question. That is not an entirely uncommon occurrence. Here is another question where I identified both stories: 1970's sci-fi short story in 4th grade reading anthology and which was not closed as a duplicate of "The Fun They Had" but has, in fact, been used as a dupe target for The Forgotten Door. The duplicate issue is where I am concerned about a lack of clarity in how to handle things.
It seems like when the querent is asking mainly about a single work, with some details from another work sprinkled in there, we can reasonably treat the question as being answered by the main work. Hence we handle the above question about two different stories that appeared in two volumes of Holt Basic Reading System as essentially a question about The Forgotten Door. Likewise, my video game question is much more about Terra Cresta than Alpha Mission.
However, it is easy to envisage situations where a question is really closer to an equal mixture of two works, which may both be identified in a single accepted answer. How should we adjudicate duplicate status in that case?