A good prep for Red Dead Redemption.
Firstly you'll notice how small the world is after the prologue. That doesn't mean you wont get tired of traversing it, and limited inceptive to explore doesn't help. Not to say mining and hunting game don't have their charm. Random bandit attacks keep your revolver at the ready too.
Story missions cover the gamut of western clichés though not nearly as much as the characters, story, and flashbacks. You'll be grateful that at least that it all moves so fast…until it's over.
You're looking at approximately 8 hours give or take on how much you fuss over side missions. I finished about 85% of the optional junk on suggestion from good old EGM back in the day. They said you could power level early on and make the story much easier; and that is true.
The meat and potatoes is grisly violent action leaning towards a Serious Sam level of mayhem. This feels wildly out of character for a Western themed game, but proves to be the highlight and developer Neversoft's greatest achievement in years.
I bout Gun for $9.99 on the PS2. Why bother with the slightly more expensive 360 version (by about $3) when Gun's achievements are the only draw (Gun on 360 is still mentioned as one of the early cop out 360 launch titles). I also had just seen Clint Eastwood's Unforgiving before buying it, so that might make me a little biased. Gun is decent time for those with loose change.