Oops! Didn't see this until just now! Too late for a chance to win, oh well.
I can share my idea anyway, right?
I have tons of RPG ideas with different universes and stuff, usually with weird quirks, but the quirks are mostly planet-specific, like bizarre planets and such. But sometimes I have a more unique quirk for the universe.
Stars aren't "fire". Now, I admit to being ignorant on lots of information about stars, and a quick check doesn't help. I know they probably aren't really fire, but isn't that a good way to describe them? It's what they look like. So, if our Stars are "Fire", think of the other elementals. My first thought was a Thunder Star. Now what about a Water Star, an Ice Star, a Wind Star...? A Light Star doesn't sound too special, a Dark Star sounds like a massive cliche, but could be quite unique. And an Earth Star doesn't sound too...exciting. Those are just the 8 RPG Maker elementals.
You might say, how does a solar system thrive on a Water Star? Well, it's a different universe. The "energy" from the Water Star can sustain life there. What about Light? Is that even necessary in this universe?
As for Sci-Fi Battlers ideas? Oh gosh I could ramble on and on, but I've seen lots of good suggestions so far. I like the Spaceship one. Don't forget some epic giant space creatures to fight in the spaceships! Cyborgs! Alien creatures that don't really fit into "medieval fantasy". Like an obligatory "not-a-Xenomorph". Maybe a living black hole?