Currently in Factoroids, the player types in the number to be "shot" before each shot.

This task is to limit the "shot" to a set of "prime number guns".  When a given prime is selected, it remains active until the player switches to a different prime.

For the first wave, only the "2 gun" is available".

For the second wave, the "2 gun" and "3 gun" are available, and likewise for successive waves, adding another prime each wave.

To select a prime, the player could have a couple of options.  First, the player could type "2", "3", "5", "7", "11", or "13" to go directly to that weapon.  If that weapon is not yet available, those keys should have no effect.

Also, we should have  "next weapon" and "previous weapon" keys to rotate through the available set.  For ease of gameplay, I would suggest 'F" and "D" as they are in the left hand home row, assuming the player is using the arrow keys with the right hand.