I liked this one quite a bit. The pixel-art is spot on, the music sets the tone nicely, and the sound effects are... well, they're really silly, but it's quite charming.
The gameplay does stumble a bit; maybe I'm going into this with too much of a Metal Gear mindset, but I was expecting to have to move to a goal, not simply to remain in one place. It wasn't until I read your responses to some of the comments here that I realised what I was supposed to do.
That being said, though, it gave me a similar feeling to playing Metal Gear games, as I lie in hiding, waiting for one of the sheriffs to get an exclamation mark above their heads, darting out of my cover, only to discover that they were going to check the cactus I just moved into.
The problem is that the player has to rely on chance; they have to take a guess as to whether the sheriff is heading for their hiding spot or another one. Or maybe you're supposed to react in time when you see which cactus the sheriff is heading towards?
Either way, nice little game.