Rochambeau

This achievement is one of about 4 that require luck to get. Every time you play Rock Paper Scissors there is a 1 in 2 chance of getting this achievement. Luckily the Rock Paper Scissors choice comes early in the game.

Latest version has a trick: If you back up to where you choose “Play Rock Paper Scissors” it will randomly pick again.

Couch Sex

Doing the Sex on the Couch path will get you this one.

Six Pack

Doing the Shopping Spree path will get you this one.

It basically involves going to the store, buying beer and drinking it all. You must go to the park or downtown before you can go to the store.

Yahtzee

This achievement is one of about 4 that require luck to get. It is the lone achievement playing the board game Pachisi, which the Things to Do With Friends path gets to. Every time you roll the dice there is a 1 in 6 chance of getting this achievement, or you can get it by winning a game of Pachisi.

You can cheat and go back before you rolled and get a different outcome. This only works on the latest version.

Dance Champion

You have to dance with Ariane 6 times to achieve this one. The obstacle here is that Ariane limits dancing to the stereo at home to 5 times. Every time you change the music counts as a dance.

So the way to get to 6 is to dance at home until she won’t anymore, then go downtown and dance at the nightclub which she will do even though she is done dancing at home.

Note the other way around does not work. Dancing downtown counts against the limit at home, so you must go downtown after exhausting the dancing at home.

It is possible to get 8 dances in a date if you go get Rebecca as Ariane will dance twice at the club, once with you and once with Rebecca and they both count.

Three Naked In Bed

You can get it with The Rebecca Trilogy 3 – Rebecca Stays The Night, and Ruins It and follow Rebecca into the bedroom.

A Quickie

This is a variation on Sex on the Couch, On the last choice of that path, select “Dismiss Yourself” instead of “Ask to stay the night”

Green Fairy

Drink Absinthe. Doing the third mini path of Drinking Problems will get you there.

Ariane Owes You A Favor

Another variation of Sex on the Couch will get you there. Once she is naked:

Touch her pussy (this is different)
Ask for oral sex (Ariane will refuse)

Lucky Spin

This achievement is one of about 4 that require luck to get.

Once you are done eating (any meal) and before you go swimming or hot tubbing, go to the kitchen for dessert and play “spin the bottle”. If it lands on Park Photoshoot you get the achievement.

You need to do this at least once while still dressed casually to reach the bikini photoshoot. Save your game before the photoshoot begins because there are two versions of the bikini photoshoot and you need them both for the shutterbug achievement.

Impromptu Strip Show

This is obtained in the Striptease at Home path.

Kitchen Disrobe

Doing the Shopping Spree path will get you there.

Cheap Thrills

This is an achievement you can get before dinner, but it results in the date ending quickly.

Bring a nice jacket (for "Cheap Thrills")
Say something funny
Kiss her
I just wanted to test if our saliva was compatible.
Turn on some music
Pick a light jazz playlist
Kiss her while dancing
Dip and kiss her neck
Go somewhere else
Let’s go to the backyard
Change into a swim suit
Follow her into the bedroom (see Ariane naked) or Change into your swim suit (Ariane sees you naked) 

The date immediately ends, but you got the achievement.

Boobie Prize

This one is unlocked by playing with Ariane’s breast too much. You can start off with Sex on the Couch but then focus on her breasts until she gives up. Or dance in the living room and keep doing “Dip and kiss her neck” over and over.