Oh I did not know there were 5 enemies and that they were tied to the blood.
I stopped after around 150 blood since I lost(or the game stopped for some reason but I'm not sure) and I didn't know there was something new if I kept going.
So I agree either a timer/a level format or just explaining this to the player can help a lot.
It's great that you are continuing with this since the base is really good and I think you can build a lot on top of this.
I will definitely play future versions :)