Thank you for the information. Every player's experience is helpful!
Shots: I think this may be partially due to your laptop monitor because many others who have played have not raised this issue. One person didn't care for the Selene flashing shots, however, and I will tone those down on next update. I'll also specifically look into the camo-issue more.
Story skipping/endings: Since you can skip story and skip missions you've completed, it only takes a couple of minutes to skip through an entire path. Therefore, I didn't worry much about the time for getting to an end again. I might put in a "Restart Story" option after you've made it through once, though, for more convenience.
Difficulty: I did test the legends on hard to make sure they're possible, and they are. I certainly don't expect players to get every one, though, and I don't expect everyone to unlock every single thing, either. Some people will be skilled enough and willing to practice enough to do it, but many won't, but that is no different than in a lot of games. The "invisible wall" was a design decision for a few reasons, but you don't need to cross it. Most shots should generally be dodged from the far left of the screen, but I think prior experiences with other shooters might lead some people to expect something different. The game was never meant to be a clone of anything else, and people who come into it with fresh eyes (less shooter experience) tend not to have an issue with the wall. The update I'm working on will increase player HP, and I will also change the exploding of the energy shots as you suggest.

I'm a bit confused by your experience, though, since on one hand each of your comments has been negative. But on the other hand, you played through all the paths, several endings, and have replayed missions and tried to get the legends. So you must be getting some enjoyment out of it. What do you like about the game?