Gateways into Madness
“If they even notice that we exist, the Gateways care nothing for us or what we want. Let’s hope that continues… or we might awaken the gods that built them.”
Russell Commons, Scientist on GST One — May 2026
Built on the Chaosium Basic Roleplaying Universal Game Engine, Gateways into Madness is an episodic science-fiction roleplaying game of exploration, mystery, impossible worlds, and cosmic horror.
Mission Briefing
Humanity’s first explorers of the impossible.
Beneath the Mountains of Madness in Antarctica, humanity has discovered an Ancient Gateway built by a civilization older than mankind.
Thrown together into ad hoc Gate Survey Teams—completely unprepared, under-equipped, and understrength—your team is sent beyond the Ancient Gateways to explore worlds no human was ever meant to discover.
Inspired by classic television adventure series, Gateways into Madness unfolds as a collection of connected episodes. Every Gateway is a new adventure: strange worlds, alternate histories, forgotten civilizations, distant futures, and places where reality itself begins to break down.
Together, those episodes slowly expose hidden truths far more dangerous than any single world waiting beyond the Gateways.
Join a Gate Survey Team.
Beneath an Antarctic research base lies an ancient gateway network created by powers that altered humanity long before recorded history. Characters affected by Advanced Gene Therapy can activate that network and are sent through it as improvised Gate Survey Teams.
They are under-equipped, understrength, and rarely prepared for what waits on the other side.
Game features
- Metamorphic effects and human-to-alien transformations
- Advantages and disadvantages for specialized characters
- Mental Fatigue and Mental Toughness under pressure
- Weapons, drones, equipment, creatures, and mission support
- Episodic campaigns connecting dangerous operations
Basic Roleplaying + Siegebreaker
Build on what works. Add what the world needs.
Gateways into Madness begins with the flexible, proven Basic Roleplaying Universal Game Engine, then adds the Siegebreaker systems this world needs: metamorphic effects, advantages and disadvantages, Mental Fatigue, Mental Toughness, modern equipment, mission support, and episodic campaign play.
That same philosophy drives Shattered Worlds Reforged and future Siegebreaker games. We build on two fantastic foundations—BRP and D&D—choosing the engine that fits the world and expanding it to deliver the experience promised by the setting.
Available Now
Cross the gateway into a growing line of missions.
Begin with the complete core game, download the free character sheet and introductory adventure, then send your Gate Survey Team into new worlds, eras, and horrors.
Gateways into Madness
Core Rulebook
The complete Basic Roleplaying-powered game of Gate Survey Teams exploring hostile worlds, alternate histories, alien installations, and Mythos threats.
Character Sheet
Player Resource
A downloadable character sheet for building and tracking members of your Gate Survey Team.
Know Your Enemy
Free Adventure
Gateway Alpha Eight leads to an alternate 1942, where the USS Jacob Jones has fired the first shots in a savage war against strange fishmen from the deep.
The Darkside of the Moon
Adventure
A Gate Survey Team investigates a functioning Ancient installation on a frozen moon and becomes trapped in the final scheme of an unhinged AI.
Rule Britannia
Adventure
Enter a dark Victorian London where the Mythos permeates everyday life beneath the Eternal Empire of Victoria the Everlasting.
What Waits in Darkness
Adventure
Travel to San Francisco in 1915 and investigate a deadly fog swallowing the Panama-Pacific International Exposition—and the secret hunting within it.
God Above the Devil Below
Adventure
A new Gateways into Madness adventure that sends a Gate Survey Team through another impossible threshold, where faith, horror, and survival collide.