STEM
NimForge
Combinatorial game theory for ages 15–18: play Nim (and its last-token-loses twist) against a perfect bot, then let the engine reveal WHY a position wins or loses — the Nim-sum, Sprague–Grundy values, and the golden ratio inside Wythoff's game. Everything computed on-device; no AI near the mathematics.
▶ Play it nowBuilt for sittings of about 25 minutes on the screen. That is our design budget, not a measurement.
#3730A3 Characters who teach
Meet the cast
NimForge's characters are realistic people, not mascots, and each one shows one idea from the math of taking-turns games. Nima adds the rows in binary, Bela knows you're safe when that sum is zero, Mirren copies the opponent, Gideon shows every such game is secretly one pile of Nim, and Minu finds the smallest move you can't make. Sabra, Iver, Wyn, and Hazel cover fixed-move games, the twist where taking the last piece loses, Wythoff's game, and games worth fractions. Professor Vera Kell sets each position and asks who wins and how you can prove it.
Nima
The Nim-sum — add the rows in binary with no carrying; the whole game lives in one number
Bela
The balance (P-position) — you're safe exactly when the Nim-sum is zero
Mirren
Symmetry — with two equal rows, copy the opponent and you cannot lose
Gideon
The Sprague–Grundy value — every impartial game is secretly a single Nim heap
Minu
The mex — a position's value is the smallest number you cannot move to
Sabra
Subtraction games — a fixed menu of moves makes the values fall into a period
Iver
Misère — the twist where taking the last token loses; one careful exception
Wyn
Wythoff's game — two heaps, a queen's move, and the golden ratio deciding who wins
Hazel
Hackenbush — games worth fractions, where numbers themselves are born from play
Professor Vera Kell
sets the position and asks who wins, and can you prove it?
What's inside
Learning goal
Combinatorial game theory for ages 15–18: play Nim (and its last-token-loses twist) against a perfect bot, then let the engine reveal WHY a position wins or loses — the Nim-sum, Sprague–Grundy values, and the golden ratio inside Wythoff's game. Everything computed on-device; no AI near the mathematics.
Mentored by Professor Vera Kell — no data leaves the device.
How NimForge handles your kid's data
- ✅ All progress, settings, and AI-generated content stays on the device
- ✅ No analytics, no tracking, no third-party SDKs
- ✅ Free — no ads, no in-app purchases
- ✅ No personal information collected from children — in line with COPPA (updated by the 2026 FTC amendments)
- ✅ No chat with strangers — play-together rooms use a short code and preset emotes, never typed messages
NimForge runs on ForgeKit — the open-source Swift Package Manager framework that powers every Spark & Anvil app. ForgeKit ensures consistent accessibility, COPPA compliance, and design language across the portfolio, so your kid's progress and preferences feel coherent across every app they touch.
Coming to the App Store
NimForge is in active development. Email us to hear when it ships — no marketing, no spam, just a one-shot launch announcement.
Email me at launch