Here is the full list of all 25 West Hunt achievements.
Claim a Twitch drop
Finish all missions in less than 3mins
Kill the outlaw in less than 1min
Kill the outlaw in less than 30 seconds
Win with a low Notoriety
Finish the game praying
Finish the game Dancing
Kill the outlaw without reading any mail
Kill the outlaw after reading more than 10 mailboxes
Win the game after outlaw runs out of time
Win the game after the Sheriff Shoots an innocent
Win the game with a high Notoriety level
Make 50 kills as a Sheriff
Make 100 kills as a Sheriff
Complete 70 Mission as an outlaw
Complete 100 Mission as an outlaw
Add one friend to your friends list
Win a game as outlaw while you lost your partner (1vs2)
Kill two outlaws in one game
Win vs Bot
Win a party 1vs1 game
Win a party 2vs2 game
Ranked on top 3 Sheriffs
Ranked on top 3 outlaws