Is it bad if I don't get it? Because I don't get it, other than the obvious vague themes. Maybe I should have played UFO.
edit: oh, I see. It almost seems a bit satirical, then. Like, there's no way that he could draw this with a straight face. I find it actually pretty funny, looking at it this way.
Sanae's world is a video game. She can death bomb and continue after dying and stuff; she is the player-character. However, the Touhous she fights aren't, and stay dead when you kill them. At the end she realizes this, and that she's permanently killed half a dozen people for not much reason. The whole thing falls flat on it's face when you realize that the Touhou game this is set in doesn't involve your opponents dying horribly and it's just Stripe Pattern being grimdark for the sake of grimdark.