Here is my public slush pile, organized by genre.

Heroic Fantasy

• A group of powerful heroes set out from the last shining city of good to reconquer the evil, swampy lowlands for humanity.
  • System: 4e/Icon
  • kinda cliche though
• Mausritter: disgraced mouse knights. Mausritter + Mythic Bastionland (???)

Science Fantasy

• The apocalypse is happening in every place, in every time. A post apocalyptic landscape with both teleportation circles and shuttle launch pads serve as strange, liminal dungeons.
  • System: Mashup of Cairn and hacks.
  • Character generation: choose or roll a time period: past, present, far future, distant future. For past, roll a Cairn character; present, Liminal Horror; far future, Plerion; distant future, Vaults of Vaarn. Then proceed as normal.
  • different players on different systems? but how fight monsters?
    • levels or no levels?

Weird Settings

• Wild west but dark fantasy creatures. Maybe some steampunk in there as well. You go to hunt down a bandit, and end up in the den of a monstrosity,

Ultralight

• Everyone wants a political/GoT/Dune style political game, yes? Then make the game entirely that. Every player is leader of a faction, and every game session is a meeting of the leaders. Very few rolls, all negotiations and debates at the table. Players make deals, strike trade agreements, and go to war. GM deals with consequences between sessions.
• To run ultralight, you must have a strong sense of expectations in genre. Not necessarily to meet the expectations, but also to subvert them in clever ways.

Horror

• Exploration as Horror: The Anti–conquistador. Journeying through strange places, seeing awful and horrible structures, fighting off creatures double your size but of a wholly inhuman shape. Players show up to the table with wonder and leave with dread as they think back on how they would ever expect something pleasant.
• Rando scenarios:
  • Human roadkill
  • ghost possessing books in a library, driving people to do awful things
  • cat-like vampire. Hyperintelligent predator.

Aphoristic System Thoughts

• Include more items, not more mechanics.

Random Thoughts

• Dune-like settings need some player powers, especially if you want to capture the politics. Players have to be someone worthwhile to have as an ally. That doesn’t need to mean survivability is high, but it does mean that you have to feel like you have some oomph behind attacks.
  • No mechanical changes necessary, just make strong-sounding monsters with mediocre stats.

Short Adventure Prompts

Next time you’re planning a new campaign or one-shot, for DnD or for any RPG, instead of having the DM decide for everyone what the adventure is, have everyone come up with adventure hooks that everyone thinks is cool. A good format for short adventure pitches is “What if we were group doing mission in setting, but obstacle.” For example,

• What if we were forensic engineers investigating a mine collapse deep underground, but the isolation may drive us crazy?
• What if we were survivors trying to make it to a safe haven in a post-apocalyptic America, but zombies with parasitic fungus crowd the cities?
• What if we were a space cleanup crew ransacking a derelict ship, but we heard something huge move down near the reactor chamber?
• What if we were the heads of rival thieves’ guilds planning heists in ancient Alexandria, but the city-state is enforcing a strict curfew?
• What if we were cavemen trying to cross the Bering land bridge, but winter is almost upon us?