I think as far as being a Fanwork goes, this game really meets the "fan" requirement. After playing the game I went and watched the KINGWORLD music video. It really is quite impressive how much in that music video is captured in this game. The enemies, the backgrounds, music, color scheme and boss, are all taken right from the music video. Even the UI seems inspired by it. The devotion of the team to FBK is really quite evident.
As far as feedback goes. Everybody has mentioned the camera, and I agree. It really is the crux of a lot of issues though. For instance, I also rarely used the dash attack due to not knowing where I would run into. The close camera also causes a lot of blind jumps or unavoidable damage.
Still, the improvement from pre-patch to post-patch is still quite noticeable. In pre-patch I literally almost never fought enemies and would just run past them since they took so long to kill. I would just try to find the nearest Sukonbu to heal. Now, I still run past enemies quite often, but occaisionally would stop and clear some out in order to make a path. The balance between Sword and gun is also way better post patch and i find myself switching between them.
I still think that the enemies are still a bit too tanky for their own good and are often in places that are difficult to attack without taking at least a little damage. The Sukonbu being full heals make this so much more doable.
The Sukonbu bonuses are a bit hard to perceive though. I don't know quite how much they improve things by but I didn't quite feel it in my playthough. Maybe a number saying how much the stat is improved by can help.
I actually quite liked the final boss. The trick is to just memorize the timing. Your eally cannot react to the boss, but memorizing the timing of the attacks makes things much more doable. I also think that completing as much as you did, with 2 levels a tutorial and a final boss is something to be proud of. It delivers a cohesive package and feels complete.