Gun Showdown on PSP came out 4 years before RDR1, and it also nails the cowboy vibe, with such a small open world and janky controls. : r/reddeadredemption
Gun Showdown multiplayer details | GamesRadar+
Retro Review - Gun: Showdown - BagoGames
Gun Showdown PPSSPP Gameplay Full HD / 60FPS - YouTube