Here are the twelve achievements available in the Steam and mobile versions of the game. I don't recommend you try for these the first time you play the game, and in fact there are some spoilers in the following hints, so you really might want to leave this section for your second play-through. Up to you, of course.

Soft Touch: Give Allen some hope before he goes. To get this one, choose the compassionate option when you talk to the ghost in the office. As long as you don't drive him off the ledge, you're good.

How do I get Allen to come inside?

Lush Life: Have a few drinks, but you might regret it in the morning. At the Park Gallery, agree to stay and have a drink, which turns into a LOT of drinks. Expect to be lectured by a number of people.

Cat Trick: Distract the cat only once. This is a matter of having Rosa stand close to the cat before you switch to Joey, because the cat is only distracted for a very short time. If you want to try for this one, save your game before you start, then restore if you miss your grab.

How do I find Frank's apartment?

Leading Lady: Get through a performance without flubbing a single line. After you've been in Frank's apartment and seen the script, have Rosa deliver all the right lines to him the first time.

How do I get through the script correctly?

Sober Solidarity: Keep a clear head, but others might think less of you. At the Park Gallery, leave after you talk to Monique. Kind of irritating that you get sneered at whether you stay and get drunk or go home and stay sober.

Wonder Woman: Defeat the Countess on your first try. In the endgame where you're on the rooftop with Joey, the Countess, and the culprit, you can take as many tries as you need to snag her with the tie. To get this achievement, you have to choose the next action correctly the first time -- that is, switch to Joey and push the Countess before she escapes from the tie.

How do I defeat the vengeful ghost on the roof?

Solo: Finish the game without asking Joey for a hint. I didn't realize you could ask Joey for a hint, actually; it's a matter of talking to him and planning your next move. His hints are rather broad, but they'll get you moving in the right direction.

Art Medium: Convince Frank you're an artist on your very first attempt.

What should I say to Claude?

Reluctant Savior: Save Charlie's life. This is a matter of having Rosa use the lit cigarette on the Countess as soon as you reach the roof, rather than just watching her strangle Charles.

How do I defeat the vengeful ghost on the roof?

Secret Finder: Find the hidden extras menu.

How do I access the secret menu?

Medium Well Done: Finish the game at least once.

Convergence Commentary: Finish the game in commentary mode, from the opening menu till the end. You don't have to listen to all the comments -- you can click through them like you do all the dialog -- but you do have to leave "Commentary Mode" switched on the entire time. As with the previous games, this is something to do on your second or third play-through.