I'm trying this out a little late and it seems like the most recent steam version has picked off some bugs, as I didn't have any problem with those. That said... eh, my opinion is a bit mixed on this. I'm giving it some leeway because it's free and early access, and I can see what it's aiming for, but I'm not too big a fan on the system it's got - having played... the English release of DaiSenKa that I can't remember the name of, this game feels like it's balanced to guarantee a few failures before reaching a single success. It also really needs a goddamn strafe button so you can aim your sword while moving and not have to pray for RNG attacks to do something, and having a basic dodge to start with would be nice, rather than having to rely on the unlock system to get a basic mechanic. That said, I feel like it's got a decent foundation to start with, just could do with some tightening up. Maybe a review later (especially as I feel that the current score is way too harsh) but probably after some more work on the game is done.
Some of the stat names are uh... less than self-explanatory. I had to switch to Chinese to see that "cm", "PS," and "PL" meant "crit damage modifier," "projectile speed," and "projectile duration" respectively. No idea what "rng" or "rad" are supposed to be. Range and radius? But then that's two stats with the same meaning. Well it matters less because...
...I think the stat display is bugged but the effects work as intended. The initial katana deals ~80damage, while the katana lv.2 deals ~150, swings faster and in a bigger arc... yeah I don't think that's a 1.02 increase.
So I think Range and Radius are supposed to be different things - Range is how far out the sword swings (i.e. 1m from character, 2m, etc), and Radius being... well, the radius of the swing (90 degrees, 180 degrees, etc). So increasing radius will hit more enemies to the side, increasing range will let you hit enemies further away.
Looks like none of the upgrades are passive stats, and instead increase maximum upgrade that you can get?
I am not sure this is a good system.
Upgrades are a little weird. Basically, to get significant upgrades, you need to pay to unlock the level in the store, then pick it up in the game. Those significant upgrades buff the weapon's stats a lot and may add additional functionality (e.g. Katana can get a wider pushback wave and eventually does a steady stream of damage straight ahead of you at significant range). However, once you hit the maximum bought level, the only upgrades to that weapon tend to be small (1-10%) general stat increases. I am iffy about this - I think it forces you to restart a number of times before you can go for a decent viable build, but this also feels central enough to the upgrade path that I'm not sure it can be stripped back out.