The vampire survivor elements were pretty clear out of the gate, as were most of the traditional upgrades (health, arrow speed, etc). I got really thrown off by the arrow upgrade system, both in how it worked and how it was presented. The hitbox of the very tall player sprite threw me off as well - I kinda expected it to be something smaller/isometric at my feet. I went into a good amount of detail in the attached video around some ideas to make the arrow stuff more clear.
Here's a playtest