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