The Rules of Invention

The heart & soul of dieselpunk.

This document provides an outline of the rules and procedures for inventions found in GURPS Basic Set. It is no substitute for reading those rules. Inventors and gadgeteers should be intimately familiar with the rules in detail, and should refer to this sheet only as a quick guide.

Required Skills

Required: Design skill from Engineering Triad or similar appropriate skill

Bonus: Weird Science allows +5

Complexity

The GM assigns Complexity.

Complexity	Required Skill Level	Retail Price
Simple	14 or less	Up to $100
Average	15-17	Up to $10,000
Complex	18-20	Up to $1,000,000
Amazing	21 or more	Over $1,000,000

Concept Roll

No bucks, no Buck Rogers.

GM rolls vs. Character Skill to determine if theory is testable.

Modifiers:

• -6 if the invention is Simple, -10 if Average, -14 if Complex, or -22 if Amazing.

Gadgeteer: -0 if the invention is Simple, -2 if Average, -4 if Complex, or -8 if Amazing.

• +5 if you have a working model you’re trying to copy
• +2 if the device already exists but you don’t have a model
• +1 to +5 if the item is a variant on a existing one
• -5 if the basic technology is totally new to the campaign (regardless of TL)
• -5 if the device is one TL above the inventor’s TL
• Weird Science: +5 if the invention is sufficiently weird

On success, inventor has successful theory and may proceed to Prototype.

On failure, inventor knows his theory is bad and may roll again next day.

On critical failure, the inventor thinks he has a workable theory and proceeds to Prototype.

Prototype

Roll vs. inventor’s skill. Use same modifiers as Concept roll, plus:

• +1 per assistant with skill 15+ (max: +4)

Each Prototype roll requires 1d-2 days if the invention is Simple, 2d days if Average, 1d months if Complex, or 3d months if Amazing.

Cost

No bucks, no Buck Rogers. The prohibitive costs of invention require a Patron or Wealth 2 or greater.

See also

Invention, Gadgeteering, and Weird Science