At the launch of the Xbox 360, several studios didn't appear to know what qualified a game as next gen, and so made games that were... cautious. We'd hate to imply that games were cynically ported over from older platforms to make a quick buck at the console's launch, so we won't. But we will note that Gun appeared on both Xbox and Xbox 360 at the same time.
So, to return to Gun is to excavate a missing link. It's a game that's partway between Xbox and Xbox 360; its low-res textures are like the feet-flippers of a Coelacanth, its blocky polygons the tiny brain-case of an Australopithecus, and its simplistic animation scraped direct from the Burgess Shale. Despite the appearance, it's very modern - indeed, it's the spiritual father of Red Dead Redemption - and (whisper it quietly for fear of Rockstar's wrath) it's a tighter story in many ways. Where RDR glories in pointless wild goose chases, Gun has a new twist at every stage.
Most importantly, like RDR, Gun is also an Anti-Western - that is, it follows a version of the Wild West that emerged in the 1960s which treats the emerging nation as bleak, dirty and over-violent. The hero, Colton White, is on a straightforward revenge quest: kill the man who killed his father. Yet, as he progresses he gradually discovers that his father wasn't who he thought he was, and that there are bigger issues for him to solve - which will require him to return to the wrecked steamboat where his father died and deeper into the Mysterious Cities of Gold.
Gun's grimness earned it controversy at the time of launch; early in the game, a railroad bridge is being blocked by angry Native Americans and you're tasked with protecting the workers. The town marshall is casually racist about the Irish and Chinese workers, and Cole is tasked to 'kill all Indians'. The real-life Apache nation took offence at this task, at the primitive and dehumanised depiction of their ancestors, and at the totally unnecessary scalping that you can carry out, and called for a boycott of the game. Activision apologised - but didn't patch the game or pull it from sale.
Sadly, like many pulp games and unlike many of the movies, that grimness doesn't cohere into a wider lesson or story, so isn't really defensible. Massacring 50 Apaches is balanced by saving a handful later? Yes, historically, Native Americans were massacred at that time, but there's no real reason to make the player complicit in that, and Gun's fiction doesn't justify it well at all.
Moral issues aside, rolling around the prairie is sedate fun. The Western environment is complex and small enough to not be boring to travel across, and varies hugely in such a small area. Even though I've played the opening sequence at least three times, and regardless of the unusual button choices, the easy gunplay makes it a pleasure to hunt wildlife, chase down wanted men and herd cattle in bucolic idyll. It's all ostensibly to make cash so you can buy upgrades, but it really emphasises how huge and diverse open-world games have become - this is about the size of just one of RDR's areas.
With that scale and a fast travel system just for story missions, you can get through the main campaign in a few hours on Easy mode. The challenge ramps up rapidly on harder difficulties (there's a famously tough fight with a priest on an armoured horse), so playing on Easy is actually the preferred option unless you're chasing Achievements.
Gun was due a sequel - a poster for Gun: Magruder's Revenge can be spotted in 2007's Tony Hawk's Proving Ground - but the trail's gone cold on us. We're sure the next Red Dead game will pick it up.