Thank you so much for the praise and feedback!
I completely agree with you, the rules could have been presented either with a more gentle tutorial / better levels or as actual text.
For Valeria the rule is that a number that you press swaps places with a number that many spaces to the right (but the glitchy numbers can't be moved, so they act as blockers)
If you ever decide to give it another try I'd love to hear your feedback on the other 3 worlds! They all feature totally different puzzles!