Expected value
Read any reward table as a single honest number, so you can compare two systems before players ever touch them.
Self-paced · Online, worldwide
The math that makes a game feel fair.
Formux Lab is a friendly course on the probability behind game systems — expected value, RNG, drop rates and variance — for designers who want their reward tables to feel great, not just look good.
Course + Ebook from $130 · lifetime access · worksheet pack included in the bundle
6core modules
38video lessons
24interactive examples
15worksheets
Curriculum
What you'll learn
Six modules, each grounded in a formula you can actually use at your design desk. No proofs for their own sake — every idea maps to a decision you make when tuning a system.
E[X] = Σ x·p(x)
How RNG really works
Pseudo-random generators, seeds and uniform draws — what "random" means to a computer, and why streaks are not bugs.
Drop rates & independent trials
Turn a wished-for feel ("about one in twenty") into a rate, then predict how it plays across a whole session.
Variance & the feel of a run
Two systems can share an average and feel wildly different. Learn to shape the spread, not just the mean.
Reward-table balancing
Weight a table so common and rare payouts sit where you want them, and stress-test it against a real progression curve.
Pity systems & safety nets
Design a floor that guarantees progress without flattening surprise — the math that keeps a long grind kind.
Sample lesson · Module 05
Reading a reward table before you ship it
Here's a full lesson in miniature. You have four rarity tiers and a target: an epic should show up roughly once every forty pulls, and the run should still hand out something satisfying almost every time.
We assign a weight to each tier, divide by the total, and read the drop chance straight off the chart. Then we check the expected value — the average reward per pull — against the effort a player spends to get there.
P(epic) = w₄ / (w₁+w₂+w₃+w₄) ≈ 0.025- 1. Sketch the feel you want in plain words, then translate each tier into a weight.
- 2. Normalise the weights so every chance is a clean probability that sums to one.
- 3. Compute expected value and variance, then playtest the numbers against a real session length.
How it works
Chalkboard first, spreadsheet second
Every idea starts as a drawing you can follow by hand, then becomes a tool you can drop into your own design doc.
01
Draw it before you calculate it
Each lesson opens with a hand-drawn diagram — a probability tree, a distribution, an outcome grid — so the intuition lands before a single formula appears.
02
Interactive examples you can wiggle
Slide a weight, watch the distribution breathe. Twenty-four small sandboxes let you feel how one number ripples through a whole system before you commit it to code.
03
Worksheet pack
Fifteen printable sheets that walk you from a blank table to a balanced one.
04
Companion ebook
Every formula and diagram in one searchable reference to keep on your desk.
05
Self-paced, forever
Lifetime access. Learn on a train, a lunch break, or a long weekend.
Who's teaching
Built by people who tune systems for a living
Formux Lab grew out of years of design reviews where the same question kept coming up: is this table actually fair, or does it just look fair? We turned the answers into a course.
- Background
- Systems and economy design across mobile and PC titles, plus a stint teaching applied probability to design students in Vilnius.
- Approach
- Plain language first, notation second. If a concept can't be drawn on a board, it doesn't belong in the lesson.
- Promise
- You leave able to defend any reward table with a number — and to explain that number to a producer in one sentence.
- Studio
- Office hours for enrolled learners with a stuck spreadsheet.
Enrollment
Two ways in. Same math.
Pick the course on its own, or add the worksheet bundle if you learn best with your hands on the numbers. Prices in USD. Payment is arranged after you send the form — nothing to enter here.
Essentials
Course + Ebook
$130 / one-time
Everything you need to think clearly about game-system probability.
- 38 self-paced video lessons
- 24 interactive examples
- Companion ebook (PDF + EPUB)
- Lifetime access & updates
Most chosen
Course + Ebook + Worksheet Bundle
$180 / one-time
The full kit for designers who want to practise, not just watch.
- Everything in Essentials
- 15-sheet printable worksheet pack
- Editable table-balancing template
- Two office-hours check-ins by email
| What's included | Course + Ebook | + Worksheet Bundle |
|---|---|---|
| Video lessons & interactive examples | ✓ | ✓ |
| Companion ebook | ✓ | ✓ |
| Printable worksheet pack (15) | — | ✓ |
| Table-balancing template | — | ✓ |
| Email office-hours check-ins | — | 2 |
| Price (USD) | $130 | $180 |
Chalk Talks
Free reading from the board
Short, practical essays that show the course's way of thinking. Start here if you're deciding whether the numbers are for you.
E[X] · 9 min read
Expected Value, Explained With Loot Drops
The single most useful number in game math — and how to read it off any reward table.
Read the talk →
RNG · 10 min read
How RNG Really Works in Games (and How to Tame It)
What "random" means to a computer, why streaks happen, and how to shape them kindly.
Read the talk →
Balance · 11 min read
Balancing Drop Rates: The Math Behind a Satisfying Reward System
Turn a feeling into weights, and weights into a table players actually enjoy.
Read the talk →
FAQ
Before you enroll
Q1 Do I need a maths background?+
No. We assume you can add and multiply and are comfortable with percentages. Everything past that — expected value, variance, probability trees — is built up from a drawing. If you've ever tuned a spreadsheet, you're ready.
Q2 Is this only for professional game designers?+
Not at all. About a third of learners are curious players who want to understand why a system feels the way it does. The examples are drawn from game design, but the thinking travels anywhere numbers meet fun.
Q3 How long does it take?+
Most people finish in about six weeks at a lesson or two a week, but it's fully self-paced and yours for life. Come back and re-watch a module whenever a new table lands on your desk.
Q4 What software do I need?+
A browser for the videos and interactive examples, and any spreadsheet tool for the worksheets. The table-balancing template works in Google Sheets and Excel.
Q5 How do I get access after I enroll?+
Everything is digital. Once your enrollment is confirmed by email, you get a link to the video course, the ebook and — on the bundle — the worksheet pack. Details are on our access page.
Enroll now
Save your seat
Send your details and pick a plan. We'll reply within one working day with a link to arrange payment and your first lesson.
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- Lifetime access once you're in
- Questions first? Write to [email protected]