Noice game! Definitely an improvement!
However, I did find this secret shop but even though I have enough points, I can't purchase anything on it.
Edit: Or is there another thing I have to do?
Right now I opt for waves to finish as the game's "challenge" is tied to the shrinking after each wave. In the future, I would like to add difficulty options but I think I would still keep waves to a set number. The inspiration here is how Killing Floor does it.
Mercenary Hunt is just a bonus mode, is not supposed to be wave-based at all, and still needs a lot of work.