I created a "reaction game" using an Arduino Mega (as it has lots of digital i/o pins), lots of ultra bright LEDs, some arcade style button, 3 Display Matrices and an EEPROM
The wiring, although there is lots of it is quite simple. Each button goes to an input pin, each LED to an output pin and the Display Matrix and EEPROM are wired up as I2C.
The EEPROM was used to store the high score tables as there are many game options.
The "Swindon Young Drivers" version simply has one mode of counting the number of correct presses within 60 seconds
My later version (pictured below) has 7 different modes, some are similar but count incorrect presses (some also deduct from the correct total),
some modes time you for 50 correct button presses (some also deduct correct presses when incorrect button pressed)
and there are also modes that only have the LEDs on for a set amount of time 0.5 sec to 2.0 secs (user configurable in 0.25 sec intervals).
Each mode has it's own 10 slot high score table.