Unique and fun idea for a puzzler!
I love the mechanic that you grow by size, which makes you actually think and not just follow the combination needed - so the levels aren't as easy as they look in the first place.
Only suggestion would to give a way to see the combination at the start of the level, instead of me just rushing to the end, seeing the string, restarting and then thinking how to solve it.
Overall, super well done!