The character you play as is called John Marston, a former outlaw who is looking for revenge on his former gang members. The world is an open sandbox where you can interact with anything you might come across. You travel most of the time on a horseback or by simply walking.
For a very long time the Red Dead Redepmtion game has only been available on Xbox 360 and Playstation 3. But recent updates has given new hope for the game to be able to play on your PC, you can read more about it here. While Rockstar is trying to make the most recent GTA available for PC-gamers, other old classics could go the same way.
The game already includes multiplayer for the consoles it supports, which is a great addon to the superb story-line. It supports up to sixteen players and there's both a co-op mode and a more competitive shooter mode. There are no confirmations on how the multiplayer feature would apply to the PC version but you can only speculate.