I think that the main character is running from a group of people. He is on a horse and he is out of water. He must be in the middle of the desert for water to be such a problem. I think that a strange wagon appears while this guy is half hallucinating.

There is a chance that the guy is following someone that he is trying to kill. I seem to remember a shootout that happens while he is very low on water. Someone gets shot in the stomach.

Any help is appreciated.

I found it.

Seraphim Falls