Tried this game for a decent amount of hours since it released. It has potential but is pretty barebones as of now.
Progression is very luck of the draw, I tried over 250 runs of this and only 2 ever got past round 20, most didn't even get past round 5.
Crit damage + Crit chance + Piercing is the only viable combo, all the other mutators barely help it would seem. Crit scales far faster than damage (+50% most of the time, compared to +18% even with damage mutator. Even with a good roll on a max level damage mutator card you can only get +48% and with a max roll with no crit mutator you can already get +75%). Also piercing makes crits really count.
The Zany is the best weapon I've seen so far (since I'm stuck at round 28), and most other weapons are barely distinguishable. For example rifles currently get +1 piercing and extremely low base damage compared to the almost half fire rate of machine guns.
Speed boss should be limited to later waves since it wipes so many potential runs its insane. Health boss is the second hardest but is mostly alright if you pick damage or piercing early on.
Energy beam special should be rarer. However specials cost should increase slower (if wave pacing is kept as it is)
Also the game has consistently crashed for me at round 28. As in completely frozen, and because the game does not save mid-run this effectively prevents me getting any further. I thought it was because of coins (because coins seem to cause heavy lag) but I collected most coins and it still crashed. Logs shown below.
