So, you start off in the classic scene from the mvie with Marty and Doc in the Parking lot. In this park choose any dialogue with the Doc. Click on the toolbox near Doc's Van on the left to get the notebook which is inside.

After talking to Doc, he will disappear. When you wake up, and after the cutscene you will be in Doc's lab. Click on the Town Sqauare model near Biff and whatever dialog you choose, he will take the Court House.

Go near George and after he takes out the Guitar, click on Marty's Guitar to take it. Use the Amplifier Controls and then use the Guitar with the Amplifier. Biff will come over and George will get into the conversation.

Talk to George and tell him:

'I can fight my own fights, Dad.'

Now use the Marty's Guitar near the Amplifier again. This will get Biff out of the way and get you Doc's Notebook. This will get you outside near the Delorian. Click on the Delorian to find Einstein. Click on the Handhel Tape Recorder on the passenger's seat and after listening to the tape, click on the Shoe on the floor to pick them up. Go out of the car and use the Shoe with Einstien.

After the cutscene, click on the Buzzer near Einstien. Edna Strickland will shout at you, and then you must select the conversation text 'I've got something for you.' and she will ask you to show her the thing. Use the Shoe with her and she will let you in.  

Once in her aparment, talk to Edna and choose:

'When did you lose your shoe?'       
'An illegal speackeasy? Cool'
'Were WAS that speakeasy?'
'What's with all these newspapers?'
'Nice Binoculars'

Now move back from Edna and on the left side you will find a Radiator. Use the Raidator to turn the Orange Valve. When Edna leaves, use the Binoculars from the table near the Television. When Edna returns, re-click on the Radiator and when Edna leaves, click on the Newspapers on the sofa to get the date.

Talk to George with any response to get into the Delorian. Click on the Time Circuit Switch, then Time Circuit Display to go back in time.

Once you get into the past talk to the lady in blue. Talk to her about anything to get her out of your way. Once she's gone, go the your left until you arrive in front of the Police Station. Now move near the window to the left side of the door to talk to Doc and choose:

'Let's go back in time'
'I guess I could brek you out of jail...'
'Where can I found your younger self?'

Now go to the Kitchen Soup on your right. After the cutscene, use the Telephone on your left. Go out of the Kitchen Soup and cross the road to get the Court House entrance and click on the door. Follow the younger Doc so that you can talk to him and choose:

'I have something important for you to do'
'When will you be finished?'
'How about quitting early?'
'You sound a little scared'
'Don't worry, I am a scientist too!'
'I hear you're working on a rocket drill'

He will cut your conversation. Use the Tape Recorder with him to record his voice. Go to the Police Station and use the Tape Recorder with the Jail Window. Go back to younger Doc and choose:

'H Equals the Hamiltonian Operator'
'I'm from the future!'
'I need you rocket drill!'
'I need it TONIGHT!'

Go near Kid Tannen and after the cutscene choose:

'I guess I'm herer to shine your shoes...'
'I'm looking for Arthur McFly'
'Isn't that Arties's hat?'
'Can I have someof those peanuts?'
'What the hell is that!?'

This will get you Artie's Hat. Go to the garden in front of the Court House and use Artie's Hat with Einstein. This will get you to the location where Arthur McFly is.

Use the Buzzer near Einstein and talk to Arthur. Anything you say won't make him leave the room. Go back to the city centre by walking to the right. Go near Kid Tannen so that he chases you on top of the Gazebo in the garden in front of the Court House. Once up there use the Tape Recorder with Tannen to get his voice recorded. To get down from the Gazebo, click on Einstein to distract Tannen. Go back to Arthur and use the Buzzer near hi door. Once he shows up to the window, use the Tape Recorder with Arthur. This will get Arthur down and you will be able to give him the Subpoena. Give him the Subpoena.  

After the cutscene head to the entrance of the garden in front of the Court House and talk to Edna, the girl near the bicycle, and choose:

'What's the scoop?'
'What's the Stay Sober Society?'
'I know where the Stay Sober Society can meet!'
'The Brown Residence'

Now leave Edna and head back to the Soup Kitchen. After the cutscene, talk to Cueball and choose:

'Could I have some soup please?'
...Salt?

Now move to the left and you will notice Cueball bumping on the red Pipe to lower down the barrels and Tannen's goon bringing in new barrels. Now click on the Kitchen's Door and you will not be able to open the door. Talk to Emmett and choose:

'I Can't get into the kichen'

Walk back near Cueball and when you hear Emmett shout 'Eureka' talk to Cue Ball and choose:

Why is the soup in a barrel?
So, this place used to be a soup kitchen?
I've got some more ideas for your soup...
...chili powder?

While Cue Ball is cooking the soup, click the red Pipe to get the Alcohol barrels on the table. Edna will come and pick up the barrels. Exit the Kitchen and head to the garden in front of the Court House and talk to Edna, and choose:

'You make soup deliveries?'
'I can help deliver the soup'
'I know a charity that needs a soup delivery'
'The Stay Sober Society'

This will get Edna to pick up the "Soup" and deliver it to the Brown's Residence. Emmett is not that happy about this, but tell him:

'They're Sober'
'They'll be quite'
'Okay then. Forget the whole thing'

This will get Emmett convinced to make the meeting at the Brown Residence. After the cutscene you will end up with Emmett in his basement. Talk to him and choose:

'Is there going to be a test on this?'

After talking to Emmett he will leave you alone to stop his father. He will argue with his father and he will give you hints on what to do. Example when he says sometime to do with fire, click on Stock Fire and when he talks about shocking or lightning click the Turn Electrical Crank or when he says food for thought click on Sprinkle Bacteria Food. Once you do it around 3 times, you will get into a converstation with Emmett. Choose:

'A month to six weeks'

Now off you go to save Doc, but unfortunately you are a bit too late. Click on the Jet Drill Remains on your left and then Click on Edna's Bicecyle. this will give you a rocket powered bike and closer to the van which is carrying Doc. Once on the Van, go to the Right and click on the Toolbox near the front wheel to get the Tire Iron. Go back to the back of the Van and go the the Left. Use the Tire Iron with the Spare Tire to get the Hubcap. Now go to the back of the van and to the Right again. Click on the Antenna to break it. Go back to the Left side and use the Antenna with the Front Window. Talk to Doc by clicking on the Rear Window and choose:

'I need a distraction!'

This will give you a chance to grab the keys. Use the Antenna with the Front Window again to get the keys to the back of the Van. Now get to the back and use the Keys with the back Doors to free Doc. When Tannen is giving you his back and he has his gun lowered, use the Hubcap with Kid's Gun. When the Gun is on the floor click on Kid's Gun to get it. Use Kid's Gun with the Shackles. Talk to Doc and choose:

'HIT THE THROTTLE!'

Now enjoy the ending and see you for Back to the Future Episode 2!