First let me get this out of the way: I've played this for probably an hour, despite what steam's weird gametime tracking thing says. I've played it on a few different computers which is probably why it says I've played it for such a short time.
Secondly: This is probably the second worst game I've gotten on Steam, the worst obviously being Air Control.
In Desert Gunner, you're a guy manning a turret. In the desert. That's literally it. The "multifacited levels" the game description promises is really just one level where your convoy drives slowly in a straight line and you shoot at things.
Unlike some of the great turret shooters out there (Beachhead 2002, lookin' at you buddy), in this one you'll have NO clue weather or not you're actually hitting anything. You fire and fire and fire and no visible damage or anything happens. Then your'e dead. Start the level over again. But when you start the level over again you won't be able to tell because the whole level is a straight line.
You can switch between guns with the WASD keys, not that the game tells you that. Also, when you start the game up, the three green dots that are offscreen on the main menu are actually "options", "credits", and "exit" respectively. You simply won't be able to read them because the game, on all three computers I've tested it on, the game insists on running on a non-native, non supported resolution.
I've tried it on a 4:3 monitor where it started in 16:9, and a 16:9 where it started in 4:3. No idea why that is, but worth noting: You won't be able to read half the main menu items.
If you're a gun-nut such as myself, you might be interested in reading the technical specs the game has on all the weaponry you'll be using. You'll be significantly less interested when you find out that most of them are downright incorrect, and all of them are wirtten in text with font so small that you can't read them.
All in all, don't waste your dollar. It's not even fun to laugh at like Air Control, it's just a mess. The developer put three seconds of effort into this, so you should treat them similarly.