I used to play with one of these every time I ended up in a toyshop that had one - for 1979 it's a pretty nifty bit of kit, even though it IS just one single chip and some resistors. Merlin plays 6 games:
Three-in-a-row (OK then, noughts and crosses)
Music Machine (bang in a tune and Merlin will play it back for you)
Echo (the game made famous by Simon a year or so later)
Magic Square (form a square of 8 lights; never did figure this one out)
Secret Number (can you guess what it is yet?)
Best of all is Merlin's 'unique' 20 sounds. Or rather, beeps.