That comic it's based on is pretty funny-paranoid. And the alt-text reminds me of a story in Blue Like Jazz, where an astronaut orbited space forever. Let's see your interpretation! :)
I didn't get why it's called 1291. Then I googled "1291" and realized that the xkcd comic this is based on is #1291. Odd title, doesn't really fit, but alright.
It's basically a dream come true for the person in the comic: we get to shoot the moon at last. C:< But the moon is fighting back with meteors, and we die in one hit. We must kill the moon before it kills us. . .
I'm really not a fan of the fact that we can't fully move around the screen in this game. I guess it makes sense, but I still feel restricted by W and S. Also the shooting in this game feels very slow and, with that slowness, tedious.
The worst thing about this game is that it basically amounts to holding down the J key and not moving AT ALL while the moon shoots projectiles in vain, because the center meteor will always hit your bullets. It makes the game quite boring and amounts to no strategy at all. And when the moon is destroyed, there's no "you did it!" or anything, you just stand there.
Overall, this was a rather bland shooter. I'd love to see a full version of this, because it's a fun concept for a game. But I didn't really enjoy that I played here. From what you've said on your blog, an expanded version does seem to be in development, so I'll look forward to it whenever it comes out.
P.S. I doubt Randall will have an issue with you using graphics from xkcd, since all the xkcd strips are creative commons. ;)