In one Alternity campaign, I had the PCs be the crew of Earth's first interstellar expedition. They were some of the best and brightest, selected from all over the world in an international mission. And so they left the gravity well of Earth, gave a quick nod to the earlier Mars colony, and took off!
They discover that tachyon-space (essentially hyperspace) is nothing like the featureless expanse theorized. Instead, it's filled with superhighways from other alien cultures. They barely navigate it and land at one alien world, which tells them that there are thousands of other worlds out there, all connected and controlled by a tyrannical alien species who controls the superhighways, and that they don't like competitors.
They rush back to Earth to warn them, but by then it's too late: The Earth is gone, removed from the solar system.
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In a homebrew D&D campaign I had, one of the PC races were a drow-like people known for being slavers. One player loved the idea, made such a PC, and before the start of the game, claimed that he was going to have fun enslaving the other PCs. I figured I'd better nip that in the bud. So at the start of the campaign, that PC's father congratulated the PC on his coming of age, stressed the importance of wise leadership, and presented him with a gift: all the other PCs as slaves. Of course, that situation lasted about as long as it took the father to leave the room. The other PCs freed themselves, let the little slaver know that they can't just order him around or he's dead meat, and everyone quickly came to a compromise. The party bonded instantly as a result, and no more threats of enslaving PCs. At least, from the other players.