from machine import Pin
import time
import urandom

led = Pin(15, Pin.OUT)
btn = Pin(16, Pin.IN, Pin.PULL_UP)

print("=== REACTION TIMER GAME ===")
print("Wait for LED...")
print("Press button when LED turns ON\n")

while True:
    time.sleep(urandom.uniform(2, 5))   # Random delay
    led.on()

    start_time = time.ticks_ms()

    while btn.value():                  # Wait for your press
        pass

    reaction_time = time.ticks_diff(time.ticks_ms(), start_time)

    led.off()

    print("Your reaction time:", reaction_time, "milliseconds\n")

    time.sleep(2)