The object of game one is to invade the enemy’s position (on the left of the screen) by firing numbers, one at a time, from your position (right side of the screen). The enemy’s number is hidden until it reaches the battlefield (the square between their and your numbers). Then if it’s lower or the same, you destroy it, your number increases by one, and you move a square to the left as the enemy sends out another number. If it’s higher, your number disintegrates and you have to fire off another one quickly as the enemy advances.

You and the enemy have a total on the far left of the screen that decreases by the number of the key you press (so you can’t send a 9 across each time or you will have run out of ‘ammo’ before long and your enemy will have an easy ride to defeat you). Sounds complicated…and without the instructions it really is!

Game two is similar to the later model MG-90 Making 10 calculator where you have a line of numbers that you have to make into a 1-9 sequence by adding or subtracting numbers 3 at a time. Should be easy but is confoundedly difficult – particularly when you start setting the problems yourself – yep, this is an interactive game. You can set how many are added/subtracted and how many numbers at a time this will affect. More fun than it sounds, but definitely one for the thinkers!