One idea could be a slime fanfic where the slime has unique powers. For example, it can transform into different shapes to help the main character in a magical world. Another idea is a slime that can communicate with animals and they all go on an adventure together.
One idea could be the slime exploring a new, uncharted part of the fantasy world. Maybe it discovers a hidden civilization of magical creatures that have unique powers and a different social structure. Another plot could involve the slime forming an alliance with a powerful but misunderstood monster against a common enemy, like an evil wizard who wants to enslave all non - humanoid beings.
Well, you could have a story where the slime girl has the power to transform into different slime forms, each with its own special ability. In the fanfic, the player discovers this and they work together to defend their village from a horde of zombies. The slime girl could turn into a super - strong slime form to fight the zombies directly, or a bouncy slime form to quickly move around the village and warn the villagers.
One idea could be a slime crossover with a popular fantasy series like 'Lord of the Rings'. The slimes could be a new, mysterious creature in Middle - earth, perhaps with unique abilities that could help or hinder the Fellowship. Another idea is a slime crossover with a superhero universe. The slimes could be experimented on by an evil scientist and gain superpowers, then team up with the heroes to fight against greater threats. And a slime crossover with a post - apocalyptic world where slimes have adapted to the harsh environment and hold secrets to survival.
Another idea is a slime oc in a modern city setting. It could be trying to fit into human society, perhaps getting a job or going to school. There could be humorous situations like the slime oc trying to understand human customs and technology.
One idea could be exploring the backstory of Rimuru's friends in more detail. For example, how did Gobta end up in the ogre village before Rimuru came along? Another could be a 'what if' scenario where Rimuru doesn't get certain skills early on and how that changes his development. Also, creating a fanfiction about Rimuru's adventures in a different part of the world that he hasn't visited yet in the original story would be interesting.
One idea could be the main character exploring a new, hidden part of the slime world that has unique magic and creatures. For example, a place filled with sentient plants that can communicate with slimes.
One idea could be that the male reader discovers the fem slime in a mysterious forest. The slime is different from the others as she has some unique powers. The male reader befriends her and they embark on a journey to find out where the slime came from and what her powers mean. Along the way, they face various challenges like other dangerous creatures in the forest and they learn to rely on each other's strengths.
Maybe an OC that is a hybrid of two different races in the 'That Time I Got Reincarnated as a Slime' universe. This OC could struggle with acceptance from both races and have to find their place. They could use their mixed heritage to develop a new form of combat or magic that is unique to them, making them a valuable asset to Rimuru's group.
One interesting aspect could be the unique world - building. It might combine the elements of slime and gamer concepts in a really creative way. For example, the slime could have special abilities that are related to gaming mechanics, like leveling up or unlocking new skills.
One interesting plot idea could be the slime exploring new and uncharted territories in the fantasy world. Maybe it discovers a hidden civilization of magical beings that no one else knew about.