Some guy on deviantART decided he wanted to make games with ponies too, so he whipped out Stencyl and wrote up a brief Flash demo for a sidescrolling shooter. It has some obvious issues (such as the fact that you can get Twilight stuck in the lower bushes and that the player can fire projectiles way too fast), but with a little work it could become something worthwhile. There's also some kind of easter egg in the project, which I haven't bothered looking for yet today.

Also, happy Remembrance Day (or Veteran's Day, if you're from the United States).