Binary Logic Game - Science Fair

An educational puzzle game I designed and built at TDK Lambda for the Big Bang Science Fair. The goal is simple: figure out the right combination of input buttons to make a signal reach the clock and stop the countdown before time runs out.

Eight arcade buttons along the bottom feed binary signals into a network of logic gate modules (AND, OR, XOR, NAND, NOR, and XNOR). Each module takes two or three inputs, applies its gate logic, and passes the result upward through LED-lit wires to the next row of gates. The signal propagates through multiple layers until it reaches the final gate connected to the countdown clock. Get that output high and the clock stops. Get it wrong and the timer keeps ticking.

The first prototype was an Arduino Nano on a breadboard wired up to discrete logic gate ICs and a 7-segment display. It proved the concept worked, so I moved on to designing custom PCBs for the modules.

The physical game uses custom PCBs with magnetic feet so the modules can be rearranged into different puzzle configurations. Each module is fully independent, with its own ATmega microcontroller that reads the input pins, applies the gate logic, and drives the output state pin. The LEDs simply follow the pin states. An 8-position toggle switch on the back of each module sets which gate type it implements, so rearranging the board and flipping switches creates a completely different puzzle.

All the surface-mount components were hand-soldered. Board bring-up involved a fair amount of bodge wiring to fix routing mistakes and test signal paths before committing to a revised layout. The controller board that reads the eight arcade buttons and talks to the timer module went through the same process.

With the bodge wires validated, the revised boards came back clean. Each module slots onto the main board with magnets, and the only wired communication link is between the button controller and the timer module, which tells the clock when to start and when to stop.

The browser version below faithfully recreates the gameplay. Hover over a button to trace its signal path through the gate network, which helps you reason about which buttons affect which gates. Three difficulty levels ramp from a simple 3-gate warm-up to a 10-gate board with inversions and trap buttons that look useful but actually break the solution.