I wonder how the levels of the characters works. In other words, how do we increase the level of a character? Is that in term of high bolt, hero bolt, creatures and/or weapons/improvements?
I think the number of hours played, and the number of world covered, are the first indication.
However, when two characters show the same data, I believe that other criteria are considered. After looking at the evolution of the level of our respective characters to me and my friend with which I play, we see that the number of weapons and the number of upgrades purchased much influence. I've always 1 or 2 levels ahead of him!
I spend each bolt as soon as I get the chance. Him, they keep them to buy every new weapon found. So I have a lot of improvements and the majority of weapons, but never a large number of bolts. But he has all the weapons, no improvement and a huge amount of bolts.