SPERM ISEKAI BATTLE ROYALE.
Basically, a bunch of dead people reincarnate into a woman who just got a nut busted into them. Twist is, they reincarnate as the sperm cell and must fight one another to decide who will be born into the stereotypical isekai world.
It'll be a fully fleshed out novel with drama, romance, betrayal, combat, and sperm super powers. May the best Sperm Cell win.