Good question: what does Gravity have that Titanic doesn’t? Both are survival tales that deal with what can go horribly wrong with the latest technology, but the eerily prescient Futility wasn’t considered sci-fi at the time. I think it’s a sign that we live in interesting times that the definition of sci-fi is getting blurry. Apollo 13 counts as historical drama despite having a very similar topic to Gravity, mostly because the events in Apollo 13 did actually happen. For comparison, The Prestige is classified as sci-fi despite occurring in our relative past, and Left Behind, although set in the future, is not sci-fi by any definition.
Your link defines mundane sci-fi as (emphasis mine):
I don’t thing Gattaca qualifies.
As to X-Men, I don’t consider them sci-fi at all, at least any more than, say, Twilight.
OK, think Gravity vs. Star Trek (ignoring for the sake of argument the factual inaccuracies in Gravity).
Gravity?
Gravity.
Ah, OK. Why is this sci-fi and not a regular drama? Because space..?
Good question: what does Gravity have that Titanic doesn’t? Both are survival tales that deal with what can go horribly wrong with the latest technology, but the eerily prescient Futility wasn’t considered sci-fi at the time. I think it’s a sign that we live in interesting times that the definition of sci-fi is getting blurry. Apollo 13 counts as historical drama despite having a very similar topic to Gravity, mostly because the events in Apollo 13 did actually happen. For comparison, The Prestige is classified as sci-fi despite occurring in our relative past, and Left Behind, although set in the future, is not sci-fi by any definition.