ROJIRAKU: Logic Gate Puzzle

ROJIRAKU is a puzzle game for learning how computers work. Connect logic gates with your finger, and step by step you will build all the way up to a working CPU of your own.

Phones and AI are, at the very bottom, just switches turning on and off. In ROJIRAKU you don't read about it. You build it with your own hands and see it work.

HOW TO PLAY
- Read the goal at the top, such as "Light the lamp only when both switches are on"
- Place gates and drag from pin to pin to wire them up
- Flip the switches: wires that are on fill with glowing red particles, so you see the result instantly
- Tap Check to try every combination of switches and clear the stage
- There is more than one right answer. Use fewer gates to earn more stars

5 CHAPTERS, 38 STAGES
Chapter 1 Gates: NOT, AND, OR, XOR, and building everything from NAND alone
Chapter 2 Combinational circuits: binary, half adder, full adder, multiplexer, decoder, 4-bit adder
Chapter 3 Memory: latches, flip-flops, counters, registers
Chapter 4 The arithmetic unit: two's complement, subtraction, shifts, zero detection, the ALU
Chapter 5 The CPU: put a control unit, a program counter, and an accumulator together to finish your CPU

WHAT YOU BUILD BECOMES YOUR NEXT TOOL
Every circuit you clear becomes a part, and in later stages you can use it as a single box. XOR goes into the half adder, the adder goes into the ALU, and the ALU goes into the CPU. In the final stage, a program runs on the very CPU you built, and the answer to 1 + 2 + 3 + 4 + 5 appears on screen.

FEATURES
- Touch first, read later. After each stage, a short note explains the circuit and where it is used in real life
- Covers logic operations, adders, and CPU basics found in school computer science courses
- A calm, textbook-like board: white background, black wires, and just two signal colors, red for on and blue for off
- A wire list lets you connect wires without dragging, and the game is playable with TalkBack
- Available in 76 languages

PRICING
ROJIRAKU is free. There are no in-app purchases or subscriptions, and all 5 chapters are free to play. Each chapter opens when you clear the previous one.
To support the app, a banner ad is shown at the bottom of the home screen and the stage list. No ads are shown on the board while you build circuits.
You can choose whether to see ads based on your interests (personalized ads) at any time from Ad settings in Settings.

Part of the RAKU series by Fuji Bit Inc.