Which Unown you get

Every Unown carries a letter, and the game keeps it nowhere: it recomputes it from the four hidden values that also decide its stats, the ones called DVs. Two Unown with the same DVs always show the same letter. And because the calculation keeps only part of each value, the letters do not come up evenly. Z is the rarest.

How this works

Each Ruins of Alph puzzle opens a set of letters. A closed letter is not a rare letter: the game re-rolls the DVs, so everything else gets likelier.

The odds, with what is open

Renormalised over the open letters, because a closed letter makes the game re-roll rather than come out rarely.

The DVs that give a letter

The calculation produces a value from 0 to 255, and ten values in a row give the same letter — six only for Z. The table gives them all, with the DVs that lead to each.