GURPS Infinite Worlds serves as the core campaign setting for GURPS Fourth Edition by Steve Jackson Games, offering a multiversal sandbox where characters travel between alternate Earths. Whether you engage with alternate histories, diverging timelines, or genre-blending worlds, this supplement provides the toolkit, world-building guidelines, and narrative infrastructure to run meta-campaigns or episodic adventures across dimensions.
It consolidates material from earlier GURPS titles such as Time Travel and Alternate Earths, while introducing Infinity Patrol and its adversarial counterpart, Centrum—a powerful transdimensional corporation.
⚙️ Core Structure
The book is divided into eight chapters:
- Infinity Unlimited – Defines the core setting of Homeline (our Earth), Infinity Unlimited, and the technology of parachronics.
- Enemies Everywhen – Introduces major antagonists like Centrum, Reich‑5 (an Axis‑won reality), and other meta‑level threats.
- Present at the Creation – Offers tools for designing alternate worlds via divergence points (e.g. Great Man or Great Moment scenarios).
- Worlds Enough – Sample alternate Earths with unique divergences, offering campaign hooks, power dynamics, and timeline flavor.
- …And Time – Covers temporal physics, paradoxes, and theories of time travel, such as plastic time and oscillating time.
- Infinite Characters – Templates for agents of Infinity or victims of anomalies.
- Infinite Campaigns – Advice on campaign goals, faction conflict, and managing multi-world continuity.
- Alternate Infinities – Sample timelines (e.g. psychic time travel society, occult cabals).
This structure allows GMs to dive in at the world, organization, or personal level depending on campaign scope.
🌍 Homeline & Centrum Framework
Infinity Unlimited introduces Homeline (Earth’s Quantum 5 reality) and its interdimensional rival, Centrum (Quantum 7), whose world‑jumping patrol fleets create political and timeline conflicts. These factions can cooperate, compete, or even clash openly, setting a stage for espionage, sabotage, or ideological warfare. The book provides in-world rationale, faction goals, and power structures to credibly drive campaigns across worlds.
🧠 World‑Building Tools
A major strength of Infinite Worlds is how it bridges storytelling and mechanics:
- Diversion-based world generation allows GMs to spin infinite variant Earths from simple premises (e.g. “What if Brutus betrayed Caesar?”).
- Temporal rules provide frameworks for how worlds diverge, how paradoxes affect gameplay, and how changes ripple across realities.
These tools cater to GMs who want to design varied campaign locales—from medieval alchemy-dominated realms to high-tech dystopias.
🧩 Threats & Adversaries
The “Enemies Everywhen” chapter outlines high-level threats like Centrum’s secret worlds, Reich-5 occult experiments, and cosmic conspiracies. While few stat blocks are included, the material provides GM fodder for building antagonists that span technology, magic, and espionage.
Additional supplementary books—like Britannica‑6 and Worlds of Horror—add depth to specific worlds, though Infinite Worlds remains the primary reference for the multiverse framework.
✅ Strengths
- Genre-Spanning Toolkit: Supports campaigns from gritty alternate histories to cosmic horror and steampunk, all under a unified mechanics framework.
- Flexible World Design: Templates and tools allow quick creation of new worlds that feel coherent and playable.
- Strong Campaign Foundation: The Infinity vs Centrum conflict provides consistent stakes across sessions.
- Wide Applicability: Works as a full setting or as a connective tissue across disparate GURPS campaigns.
⚠️ Limitations
- Sparse Mechanical Examples: Some reviewers noted it lacks clarity in describing how conveyors or projectors function, requiring GMs to supply details or extrapolate from prior supplements.
- Capsule World Descriptions: Most world profiles are brief—only a few settings (e.g. Britannica‑6) receive deep coverage, leaving GMs to flesh out the rest (which can be aided by genre supplements such as GURPS Fantasy, GURPS Space, and others).
- Requires GM Commitment: Running a multiverse campaign demands preparation to keep numerous settings, timelines, and factions coherent over time.
🧭 Community Perspective
Forum feedback emphasizes:
- Enthusiasm for the multiverse concept, particularly among groups wanting sandbox freedom and cross-genre exploration.
- Caution from some users: Infinite Worlds is powerful, but demanding—especially if you’re aiming for detailed world-building or ideological nuance between factions like Homeline and Centrum.
🧩 Final Verdict
GURPS Infinite Worlds is a masterful and essential supplement for players and GMs who want more than a single setting—they want infinite ones. Its mix of high-level agency, alternate-world design aid, and shadowy factions offers endless possibilities. While not plug-and-play in the traditional sense, its utility lies in its vision: a connected multiverse built around player agency and narrative choice.
