Marginal Sales vs. Marginal Effort

Is additional effort worth the additional sales?

20/80 Dev Time Rule

The final 20% of development takes as much as 80% of the total development time.

Dev Time Estimation Rule

Multiply your time estimates by 3 for a much more realistic picture of actual dev time.


Having a large number of ongoing occurrences beyond the initial spike (high standard deviation).

Illusion of Control

Overestimation of one’s ability to control activities or events.

Parkinson’s Law

Work expands to fill available time.


Assume failure then figure out how it happend. This is a method of risk identification.

Gambler’s Fallacy

The belief that one win will lead to another, or past failures necessitate?more failure.

Product Life Cycle

How sales volume and customer characteristics change as a product ages.


Selecting a sub-optimal decision for the purpose of saving time.

Law of Small Numbers

Variability is high in small sample sizes.

Regression to the Mean

Over time, outcomes tend to average out.

The Experimental Approach

Tackle unknowns through designed experiments and analysis.

Success and Luck

Is success largely beyond our control?

Probabilistic Thinking

Thinking in terms of the variability of outcomes rather than in discrete terms.

Cognitive Switching Penalty

The price you pay for multi-tasking.

Contingency Planning

The importance of developing backup plans, because things will go wrong.

The Toxicity of Long Hours

Mental degradation, inefficiencies and other ill effects from overwork.

Opportunity Cost

The cost of what you are giving up when you make a decision involving scarce resources like time and money.

Expectation Management

Tempering expectations to avoid hype and eventual disappointment. Important due to sensitivity to loss.

Exponential Effects of Scope Creep

How scope creep leads to exponential increases in dev time.

Self-Fulfilling Prophecy

Existing beliefs create a feedback loop that reinforces the belief or influences its outcome.

Timmy, Johnny and Spike

Segmenting your target audience to better understand the breadth of user experiences and wants.

Contradiction of Passion

Many devs are inspired by passion for making games, but they need to make decisions dispassionately to be successful.

4:44 Rule

For 48 hour game jams spend the first 4 hours building the core mechanics and the next 44 on polish.