I respect that you wrote a game in C using SDL! Maybe I should try that someday.
I liked the game as it brought me back to the days of yore - that is when game like Galaxian or Galaga were what we were playing! Having to time the shot on a slightly delayed firing canon to launch that slow-seaming laser bolt so it arrives just in time to obliterate the enemy! Good times!
The sound track was awesome! That alone is worth the price of admission - if it weren't free :)
I guess I would change the orientation to be vertical rather than horizontal now that I think about it. But no points off for being original.
My game isn't a blast from the past, but rather a nod to the future. Not of gaming, but of humanity. Specifically when we've sucked this rock dry and have to tuck our tails between our legs and scurry off to another world to destroy. Let the good times roll!
Anyway, if you could give my game a try if you haven't, rate it and let me know what you think in the comments, I would respect you even more!
P.S. I just made that back story for my game up just now. But I kinda like it. :)