Even with the extra exp. the max you can reach is lvl 40 if you're lucky. also no idea about the evolve thing, I tried maxxing a single skill but I couldn't

I survived more than 15 minutes and didnt get the achievement for it. Is it broken?

the large purple ghost that appears seems intentionally made to kill you once you reach the 30 minute mark. However, it seems like it can take damage just like any other boss, although it has more health than one (a direct impact with max upgraded Fire At Will with the extra damage trinket did not kill it, which seems to be able to one-shot everything else). Has anyone managed to kill it, and if so, what happens after?...

I notice there have a achievement "King of magic?" but I have no idea how to complete it. Is it completed by purchase all upgrade in Power Up or beat the huge purple ghost after 30min ?

I like what yall have done here its a nice game. very much like Vampire Survivors. if you guys could add a Co-op mode you could stand out from VS and have a lot more people have interest in your game.