A quick note before you play
Wait for the green signal, then tap. See your reaction time in milliseconds. Start when you are ready. You can restart at any time, and keyboard controls work after you select the game area. On touch screens, use the on-screen controls or tap the board. No score is uploaded, and there is no account to create.
Build a reaction timer with reliable states ↗
Handle early taps, randomized waits, timestamps, and restart cleanup in the Reflex Lab source.
Make your own version
This game is also a free template demonstrating random delays, timestamps, and early-input handling. Download its source to explore the logic, change the visuals, and experiment with a new rule.