Red Dead Redemption and Undead Nightmare Differences?

There is no stores, no train opertational(zombies why would there be a train, they'd be eaten), no banks , and the animals are undead. But You get your weapons from saving settelments/the major cities in the game, you can still kill the innocent, their is find and save missions instead of bounties. I enjoyed it alot, but after beating the story, having all the weapons and so on I lost interest as my friend used all my ammo up which in UN is somewhat scarce for awhile. There is no weapons packs for it.