Here is the full list of all 10 Blackwell Unbound achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Finish the game at least once
Make an unusual phone call
Get hit by the saxophone only once
Take all four photographs
Find the game's blooper reel
Smoke at least 100 cigarettes
Smoke less than 20 cigarettes by the end of the game
Find the floating head easter egg
Listen to all of Lauren's dreams
Play the game in commentary mode, from the opening menu till the end