Let's say I want to program the option to seed my game so that friends can share randomized levels and features.

I grant myself a 25-digit "number", digits can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z

so a number could look like this: z5a83nd83jsw201n4j5b692001

How do I program a function to look at that digit by digit and say: the first digit is z, therefore level 1 will use this tile... the second digit is 5 so the first level will also have this monster...

What would be the best way to get such a function working? Sorry to get so abstract. It's just an idea, but I'm not sure how to go about programming the game to recognize these numbers.