Here is the full list of all 30 The Darkside Detective achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Slack off the job and read a trashy mag in each case.
Read all the book titles in the library.
Search 10 bins.
Close case 7: Buy Hard
Fully explore the vents
Play games in arcade
Use the kango hammer on everything in the sewers before advancing.
Enter the Cursed Lodge.
Take all of the Turner's calls in the Bloodwolf HQ.
Listen to all of Dick Brickman's radio shows. Featuring Dick Brickman.
Remember neglected responsibilities
Take a photo at the photobooth
Watch the credits to the end.
Close case 6: Don Of The Dead.
Examine 8 cars.
Close case 5: Loch Mess.
Close case 4: Police Farce.
Give Laxatives to McKing.
Close case 3: Disorient Express.
Complete the virus minigame in three steps.
Listen to all of John's gags.
Spot the Darkside SkyBeast.
Close case 2: Tome Alone.
Check Roy's Alibi
Close case 1: Malice In Wonderland.