This achievement is story related and cant be missed. It will unlock after freeing Emmet from the ropes at the courthouse.
Citizen Plus Treatment Center
Press to interact with the intercom
Press to interact with the intercom
Dialog (Guard) - Why's my stuff locked in a cage?
Dialog (Guard) - Can I take a look at my stuff?
Press to interact with the Window (above the poster)
Press to interact with the Squawk Box
Dialog (George) - Is there a way I could talk to Jennifer?
Press to exit the conversation
Press to interact with the Squawk Box
Dialog (George) - I tried to peek past the guard
Press , select Marty's Guitar and press to equip
Press to use Marty's Guitar with Squawk Box
Press then press to stop using Marty's Guitar
Press to interact with the Door
"The Power of love?" unlocks
Walk past Jennifer's Door
Press to interact with the Food Tray
Press to interact with the Door behind the food tray & guard
Press , select 1986 Newspaper and press to equip
Press to use the 1986 Newspaper on the Crack Under Door
Press to interact with the Intercom next to Biff's Door
Dialog (Biff) - Eat Your Pill
Press to interact with the Newspaper
Walk back to the Guard
Press , select Pill and press to equip
Press to use the Pill on the Soda
Press to interact with the Control Panel
Press to interact with the Volume Slider
Press to interact with the Olfactory Slider
Press to exit
Walk left to the Door
Press to interact with the Door
Press , select Marty's Guitar and press to equip
Press to use Marty's Guitar on the Microphone
"Free Citizen Brown" unlocks
Hill Valley 1986
Dialog (Doc) - What do we do now?
Dialog (Doc) - Where IS the DeLorean, anyway?
Dialog (Doc) - What was Edna doing to you?
Dialog (Doc) - Why'd you marry Edna, anyway?
Try to move
Dialog (Edna) - Doc's REAL wife is way cooler than you.
Dialog (Edna) - He's capable of doing great things without you.
Dialog (Edna) - You inspired him to do bad things.
Hill Valley 1931
Dialog (Doc) - Any
Dialog (Doc) - Any
Press to interact with Emmett
Dialog (Emmett) - Any
Dialog (Emmett) - Any
Dialog (Emmett) - Any
Dialog (Emmett) - Any
Press to interact with the Courthouse Doors
Hill Valley High School 1931
Press to interact with Edna
Dialog (Edna) - Any
Dialog (Edna) - Any
Dialog (Edna) - Any
Press to interact with Edna
Press to exit the conversation
Press to interact with the DeLorean
Walk over to the front of the school
Press to interact with Trixie
Dialog (Trixie) - Help me make Edna jealous!
Press to exit the conversation
Press to interact with Edna
Dialog (Edna) - I talked to Trixie
Press to exit the conversation
Walk Right towards the Truck
Press to interact with Cueball
Dialog (Cueball) - Will you be playing for Trixie later?
Dialog (Cueball) - You seem angry about Trixie
Dialog (Cueball) - What's so toe-curling about Trixie's past?
Dialog (Cueball) - My mom came on to me
Dialog (Cueball) - What's with your teeth?
Dialog (Cueball) - Seriously, about your teeth
Press to exit the conversation
Press to open your inventory
Select the Postcard and press to examine it
"There's a Moose?" unlocks
Press to exit
Press , select Algae Cakes and press to equip
Press to use Algae Cakes on Cueball (1/7)
Press to use Algae Cakes with Guy (2/7)
Press to use Algae Cakes with Edna (3/7)
Press to use Algae Cakes with Arthur McFly (4/7)
Walk towards the screen
Press to use Algae Cakes with Trixie (5/7)
Walk back to the DeLorean
Press to use Algae Cakes with Doc (6/7)
Walk back to the front of the building
Press , select the Postcard and press to equip
Press to use the Postcard on Edna
Press to interact with Trixie
Walk right to the Hill Valley of the Future Exhibit
Press to interact with the Train of the Future
Dialog (Edna) - Any
Press to interact with the Button
Wait for the booth to stop talking
Press to interact with the Third Button from the left
Press to interact with the Fourth Button from the left (while the other button is still active)
Press to interact with the Diamond shaped prism
Press to interact with the Street
Emmett's Lab
Press to interact with the Oil Can
Press to interact with a Stack of Mind Maps
Press to interact with a Stack of Mind Maps
Repeat until Emmett mentions the 90% Hooligan rate
"Edna Was Right!" unlocks
Press to interact with Odd Looking Printer
Press to interact with Mind Map Test Switch
Press , select Algae Cakes and press to equip
Press to use Algae Cakes on Emmett (7/7)
"Let Them Eat, Um, Cake" unlocks
Press then press to stop using the Algae Cakes
Press to interact with Slide Advancer
Press to interact with Stew Pot
Press to interact with Slide Advancer
Press to interact with Valve
Press to interact with Valve
Press to interact with Slide Advancer
Press to interact with Stew Pot
Press to interact with Stew Pot
Press to interact with Slide Advancer
Press to interact with Valve
Press to interact with Valve
Press to interact with Slide Advancer
Press to interact with Stew Pot
Press to interact with Stew Pot
Press to interact with Slide Advancer
Press , select Mind Map and press to equip
Press to use Mind Map on Mental Alignment Meter
Press and then press to stop using the Mind Map
Press to interact with Easel
Dialog (Emmett) - It's not so good
Press , select Mind Map and press to equip
Press to use Mind Map on Emmet's Mind Map
"A Not So Beautiful Mind" unlocks
Press to interact with the Photo Album
Press , select Oil Can and press to equip
Press to use Oil Can on Emmet
Press then press to stop using the Oil Can
Press to interact with the Cleanser Shower
Press to interact with the Cleanser Spray Bottle
Press to interact with the Exit
Press to interact with Emmett
Dialog (Emmett) - You can't marry Edna!
Dialog (Emmett) - You're too young!
Dialog (Emmett) - You're supposed to marry someone else!
"An Uncomfortable Truth" unlocks
Dialog (Emmett) - Forget it…
Press to exit the conversation
Press to interact with the Exit
Hill Valley High School 1931
Walk over to the Hill Valley of the Past Exhibit
Press , select Spray Bottle and press to equip
Press to use Spray Bottle on Caveman
Press to interact with the Caveman
Press , select Photo Album and press to equip
Press to use Photo Album with Trixie
Press , select Diamond Shaped Prism and press to equip
Press to use Diamond Shaped Prism with Trixie
Press , select Mink Stole and press to equip
Press to use Mink Stole with Trixie
"The Other Woman" unlocks
Walk over to the DeLorean
Press , select Spray Bottle and press to equip
Press to use Spray Bottle on DeLorean
Press to interact with the DeLorean
Press to interact with Doc
Dialog (Doc) - The light's green!
Press to interact with the DeLorean (If the light isn't green wait a few minutes and try again. Once the light turns green proceed to the next step.)
Press to interact with Doc
Dialog (Doc) - The light's green!
"Like a Not-So-Fine Wine" unlocks
Emmet's Lab
Dialog (Edna) - Carl Sagan wants to talk to you
Dialog (Edna) - He has a lead on the "Speakeasy Arsonist"
Press , select Spray Bottle and press to equip
Press to use Spray Bottle with Emmet
Hill Valley High School 1931
Dialog (Doc) - Any
Dialog (Doc) - Any
Dialog (Doc) - Alone and miserable
Dialog (Doc) - She turned you into a puppet!
Dialog (Doc) - Any
"Timely Traveler" unlocks
Press , select Oil Can and press to equip
Press to use Oil Can on Emmet
"Breaking Up is Hard to Do" unlocks
Courthouse
Dialog (Emmett) - Any
Dialog (Emmett) - Any
Dialog (Emmett) - Any
Dialog (Emmett) - You care about inventing!
Dialog (Emmett) - Um...
Dialog (Emmett) - You care about me!
Dialog (Emmett) - No
Dialog (Emmett) - I did it for the hell of it
Dialog (Emmett) - You're delusional!
"Your Own Personal Frankenstein" unlocks
Press to interact with Emmett
Dialog (Emmett) - Got anything useful?
Press to exit the conversation
Press to interact with the Rope
Press to interact with the Down Arrow
Press to interact with the Cleanser Spray Bottle
Press , select Spray Bottle and press to equip
Press to use Spray Bottle on the Rope
Press then press to stop using the Spray Bottle
Press to interact with the Courthouse Doors
Press to interact with the Rope
Press to interact with the Left Arrow
Press to interact with the Right Arrow
Press to interact with the Left Arrow
Press to interact with the Right Arrow
When you are near Emmett, Press to interact with Emmett
Press , select Spray Bottle and press to equip
Press to use Spray Bottle on Emmet
"To The Expo!" unlocks