Abstract
Problem: RPG character creation systems often rely on invisible rules, arbitrary restrictions, and post-hoc constraints to prevent unviable builds — leaving players confused about why their choices are being overridden.
Approach: Tim Cain proposes using geometric shapes (specifically triangles) as the constraint mechanism itself, replacing hidden rules with spatial relationships that players can see and manipulate intuitively.
Findings: The concept was prototyped and implemented in The Outer Worlds but didn't fully land with playtesters. Cain believes the core idea is sound but needs someone to crack the right implementation.
Key insight: If you encode your constraints into the shape of the system rather than bolting on rules after the fact, players never encounter a "you can't do that" moment — every configuration they can reach is valid by definition.
1. The Dice Problem
Tim opens with a thought experiment: you're designing a tabletop RPG using two six-sided dice (2d6, generating 2–12). You want ones to trigger bad outcomes, sixes to trigger good outcomes, and rolling a one-and-six to trigger something special. But the math doesn't cooperate — double ones (double bad) and double sixes (double good) occur at undesirable frequencies, and the special one-six combo is too rare.
The typical game design fix is to pile on rules: treat double ones as a one-and-six, force re-rolls, or add conditional logic. Players have to memorize these rules (tabletop) or watch unexplained things happen on screen (video games).
2. The Geometric Fix
Instead of adding rules, modify the dice themselves. Replace the six on the "bad die" with a second one (giving you 1, 1, 2, 3, 4, 5) and replace the one on the "good die" with a second six (giving you 2, 3, 4, 5, 6, 6). Result: double ones and double sixes become impossible, one-six combos become more common, and the player just rolls — no rules to remember, no hidden re-rolls. The geometry of the dice is the constraint.
3. The Triangle Attribute System
Tim presented this idea at the Reboot conference in Dubrovnik, Croatia in 2017. Starting from Fallout's S.P.E.C.I.A.L. system, he drops Luck (which he'd now implement as a multi-level perk rather than an attribute) and groups the remaining six attributes into two triangles:
- Physical triangle: Strength, Agility, Endurance
- Mental triangle: Perception, Intelligence, Charisma
Each triangle can be rotated. Point the triangle up, and the top attribute is high while the bottom two are moderate. Point it down, and the top two are good while the bottom one suffers. The player spins the triangles to shape their character. Every possible orientation produces a valid build — no "unviable character" states exist.
3.1. Primary and Secondary Groups
Players can also designate one triangle as primary and the other as secondary. The primary group gets a small bonus across all three attributes regardless of orientation, giving another axis of customization without additional rules.
4. Why This Matters
Tim's core frustration is with the "hand of the designer" reaching in to invalidate player choices:
- AD&D: If you rolled two attributes at 5 or below, your character was unviable — an unwritten rule players had to just know. The official rules forced you into specific classes, creating impossible multiclass situations.
- Point-buy systems: Hidden floors and ceilings prevent certain attribute distributions. Players discover constraints only when the system refuses their input, often without explanation.
- Video games: Re-rolls and corrections happen silently, leaving players wondering why their dice changed after landing.
These are all symptoms of the same problem: the designer built a system that permits invalid states, then patched it with rules that feel arbitrary. Geometric constraints eliminate invalid states at the structural level.
5. The Outer Worlds Experiment
The triangle system was actually implemented and functional in The Outer Worlds. However, it didn't fully achieve its goals — some playtesters felt locked out of certain character concepts, while others were confused about what the triangles were doing. Tim is candid that the implementation didn't land, comparing it to his decades-long quest to implement pure flaws in an RPG (which he eventually achieved in The Outer Worlds through a different approach than Fallout's traits/backgrounds system).
6. An Open Challenge
Tim closes by framing this as an unsolved design problem. He believes geometric constraints are fundamentally the right approach — replacing arbitrary rules with visible, manipulable spatial relationships — but acknowledges he hasn't cracked the ideal implementation. He explicitly invites other designers to take the idea further.
The principle extends beyond character creation: anywhere a game system uses random generation plus corrective rules, there may be a geometric reformulation that makes those rules unnecessary.
7. References
- Tim Cain. YouTube video. https://www.youtube.com/watch?v=RfNtPr7LeGQ