Thank you so much for playing! I'm glad you enjoyed it overall! This is an on-going project, so it'll probably continue to receive tweaks and balance as I work on it.
The boss fight is going to be tough, I'll have to keep watching feedback. I've had at least one player think it's too easy. Be sure to pick up the money on the way through the level, and heal up at the vending machine on the far left on the bottom floor before taking on the boss. You'll retry with whatever health you enter the fight with. I'll considering updating this in the future though, maybe a heal boost on each retry.
As for strategy, there are two phases. On the first phase (the small floating warlock) the best strategy is to quickly finish off the 2 crows, as they actually pack a solid punch if you ignore them. After that, the uppercut attack is probably the best against him, though the 3-hit punch combo allows you to briefly hang in the air, and is also effective. If you find health and power running low, the green seals can be destroyed for 1-3 orbs. If you destroy all 4, the boss will respawn them allowing more harvesting. This only works on the 1st phase though.
Once you get the enemy's health to 75%, it'll switch to the 2nd phase. This part needs some work, but there's a simple strategy right now, assuming you can get here with a decent health pool. Just avoid it's volley of ranged attacks, and once it starts to follow you just beat the tar out of it. It's large, so basic attacks should connect easily. It has a "drain" attack, but if you have the health and keep pounding it, you can beat it! That said, next update (it may be a little while) I plan to change the attack pattern a bit. This being a demo, there's just a little story afterwards, and that's about it. I do intend to continue and expand the game though! Once it's long enough, I intend to build in save slots and other helpful things.
Thanks again for your feedback, it's very helpful! :)