Level 99 happens to be the max - though that does leave you with 7 extra skill points. It is possible to have a full set of legendary gear as well btw, there are legendary potions it took me a while to find two.
Okay am I missing things, or have I reached the end? I easily get into the trillions of blood and theres nothing left to construct or any upgrades that have a max level (obviously you can endlessly upgrade some of the things), all I see now is just to keep on shattering runes endlessly and slowly crawl up the levels and get more trophies and rune shatters.
Bug - if a block were to soar into an explosion block and then you move the explosion block just before the block hits it, the block continues moving and passes through obstacles.