This is an exercise in basic Scratch features using variable, methods, and custom block. The game itself is a Prime Number tester which "remembers" prime factors as you play the game. For example, the number 2147483647 (a prime) will take a few seconds to compute as a prime the first time you run it. The subsequent times, however, will run in less than a second. This relies on a list of prime numbers that are stored and retrieved. In most classic examples for testing for primality, a loop runs from 1 up to the number being tested. In fact, the most efficient test is to test for divisibility of only the prime numbers less than the square root of the number. P1 .. Pn < sqrt(m) This is a fun exercise, but does prove to test the limits of the procedural basis of the language (at least as far as I can tell so far) in how to isolate functional code. HOPE SOMEONE FINDS THIS USEFUL.