Where to start
Games where you build a computer from logic gates
Building a computer from nothing turns out to be one of the most satisfying puzzles there is, and there is now a small genre of games about it. Here is an honest map of it, NANDSIM included, so you can pick the one that suits you.
The short version
| Name | What it is | Platform and price | Best for |
|---|---|---|---|
| nand2tetris | A course and book (The Elements of Computing Systems, Nisan & Schocken) that builds a computer from NAND up through a compiler and OS | Free online materials and Coursera course; book from MIT Press | Learners who want the full stack with structure and exercises |
| nandgame | A browser puzzle sequence from NAND to a programmable computer | Browser, free | A quick, focused tour with no install |
| Turing Complete | A polished puzzle game from gates to a CPU you program in your own assembly | Steam, paid | Puzzle-game fans who want a long campaign and a story |
| Digital Logic Sim | Sebastian Lague’s free logic sandbox, made alongside his YouTube series on how computers work | Desktop, free (itch.io) | Free-form tinkering after watching the videos |
| MHRD | A hardware-design game where you write a hardware description language instead of drawing wires | Steam, paid | People curious about HDL-style design |
| Shenzhen I/O, Silicon Zeroes | Puzzle games about circuits and microcontrollers at a higher level than gates | Steam, paid | Zachtronics-style optimisation fans |
| Logic World | A 3D sandbox where you build circuits as physical objects | Steam, paid | Big creative builds, Minecraft-redstone style |
| NANDSIM | A browser puzzle game from one NAND to a CPU with your own instruction set and assembler, plus sandbox, daily challenges and a museum of historical computers | Browser, free | See below |
nand2tetris: the classic course
If you want to study how computers work, start here. Noam Nisan and Shimon Schocken’s course walks from NAND gates through the Hack computer, its assembler, a virtual machine, a compiler for a small language and an operating system. It is free online, the book is excellent, and the Coursera version has taught hundreds of thousands of people. It is a course rather than a game: you write chips in a simple hardware description language and test them against provided scripts. Our page on the Hack computer explains its design.
nandgame: the quick tour
nandgame runs in the browser and takes you from a NAND gate to a working computer in a sequence of compact levels, mostly following the nand2tetris path. It is free and fast to start, and it has been a favourite on Hacker News for years. If you want a few evenings of focused puzzles, it is a great choice.
Turing Complete: the big puzzle game
Turing Complete is a commercial game on Steam with a long campaign, a light story, a level map and a strong community. You build up to your own CPU and program it in an assembly language you define. It is very well regarded by players, and if you enjoy it you will probably enjoy everything else on this list.
Digital Logic Sim and the videos
Sebastian Lague’s video series on how computers work is one of the best visual introductions anywhere, and his free Digital Logic Sim lets you build along. It is a sandbox rather than a puzzle game, so you set your own goals.
Where NANDSIM fits
NANDSIM is a game first. It aims for the depth of the bigger titles in a free browser tab:
- Puzzles say what, never how. Each level gives behaviour (a truth table, a timing diagram, a job for your computer) and checks your circuit thoroughly. Any circuit that behaves correctly passes, and stars reward fewer gates and shorter delay.
- Your computer is really yours. No CPU is prescribed. You choose the ALU operations and their opcodes, define your instruction formats, and the game assembles your programs onto your hardware.
- It keeps going after the CPU. Optional challenges cover faster adders, multipliers, caches, pipelining, interrupts and multicore. There are also daily, weekly and monthly challenges, endless contracts and player-made levels.
- Play together. Co-op rooms let friends build the same machine at once.
- A museum. Famous machines such as the Manchester Baby, 6502 and RISC-V are rebuilt from NAND gates so you can run their programs and look inside.
- Fast. The simulator is written for millions of gates, so big designs stay interactive.
If you want a tool, not a game
For coursework and free-form design, the standard tools are Logisim-evolution and Digital (both free desktop apps), and CircuitVerse in the browser. Many university courses use one of these, and they are excellent at what they do. NANDSIM’s sandbox covers casual use, but if your course specifies one of them, use that.
Which should you pick?
Want a structured course with a textbook? nand2tetris. A short, free browser tour? nandgame. A long commercial puzzle campaign? Turing Complete. A free browser game that goes deep, with your own ISA, co-op and historical machines? Give NANDSIM a try. Many people end up playing more than one. The ideas transfer, and each game shows the same machine from a different angle.