I love how everytime a Cave thread comes up, someone posts that stupid-ass last boss Mushihime video.
Here are some things to consider,
-The majority of the game is not like this at all, and is quite manageable
-That's a really hard boss on the hardest difficulty level
-The majority of players will never even see this boss
-By the time you actually can face this boss, you'll be good enough so that you can probably put up a decent fight, as a good player can see the survival lines
In other words, posting that "crazy" video and commenting about how it doesn't "look fun" is essentially holding up a sign saying "I'm a huge n00b and know absolutely nothing about the shooting genre". It would be like me posting a video of a tough battle on Halo 3 Legendary or the hardest song in Rock Band and assuming that the entire game is like that.
Danmaku games are no harder than the oldskool shooters, just that your hitbox is smaller and there's more bullets, as opposed to having a huge hitbox but less bullets. I consider Danmaku games to be easier, since you know exactly where your hitbox is and there's no questionable hits that can come up in the other games.
