Here's a walkthrough that avoids any major story spoilers. This demo isn't particularly difficult. Most of the story puzzles involve little more than talking to people or giving them items. So this is really for people feeling impatient or bored with the demo.
This only covers the mandatory events. There are several optional events throughout the demo that aren't covered here. There are three endings and two of them can only be reached by completing some of these optional events. The conditions for these other two endings are listed after the main walkthrough.
Let's start with a few ways to get hints in the game:
Pressing the C button brings up the status screen which has a hint. This generally gives you a pretty good idea what to do next.
The information desk often has hints too. Usually if a store is mentioned it means there's some sort of event there you need to attend.
The Store News category usually deals with events of that day while Rumors might have hints that are useful later.
November 19, 1989
The first day serves as a basic tutorial level.
Start by talking to the customer and answering their follow-up questions.
Then take any three games from the store. You can find them by pressing the A button near the back wall or racks on the right and selecting Take.
Try giving all three games to the customer. After that doesn't work try taking another game from one of the shelves.
After a scene you can now ring-up the customer, Use the Cash register to finish this task.
After another scene you're free to explore the mall. It's after closing time so this is where you learn about needing keys to enter stores after-hours.
Make your way to the parking lot and Use Dani's car to complete the day.
November 24, 1989
In the second day there are multiple tasks that need to be completed to advance the story.
You start the day off as Dani. She has two required tasks that don't need to be completed in order. The first is going to Video Buffet and talking to D.B.
For the second task you need to Talk to Todd at Checkers.
Agree to help him to continue. Selecting the second option is fine but you'll eventually have to come back and select the first.
The first customer will leave after you Talk to him a few times.
The second customer will also leave after some dialog. Your responses to her questions impact the story a little.
Talk to the third customer.
Now show them a suit by selecting Use on a mannequin.
Show them the teal suit next.
Use the Cash register to finish up.
After completing these tasks, the story can be advanced by returning to Denim Country.
Before you can leave Video Buffet you have to Talk to Grunberg who gives you an item.
Try giving the item to Annette at Sunset Video.
After that you can give the item to the Security guard.
Now go to Denim County and Talk to Dani.
Again Use Dani's car to complete the day.
November 26, 1989
You begin this day as D.B. and will be assigned two tasks that must be completed to advance. They can be completed in any order.
The first task can be completed by Giving the item you start with to Gary at the Cavern. This will result in you getting another item for later use.
The other task starts by Talking to Charles at ThoreauBooks.
Completing the second task requires talking to three other employees in any order. Carol who works in the south center hallway is one of them.
Scott at Transistor Lodge is another employee you need to talk to.
Annette at Sunset Video is the third employee you need to talk to.
After talking to all of them, Talk to Charles again.
After completing all these tasks you can return to Video Buffet and Give the item you have to Grunburg.
After switching to Dani head over to Video Buffet for a scene.
Now you need to talk to all the employees at Fish or Cut Bait. The order doesn't matter.
One employee is behind the counter north of the entrance.
The other employee is in the fishing section west of the entrance.
Now you need to go to the south hallway and Talk to Jordan who is at the payphone.
Return to Video Buffet and Talk to D.B. to advance to closing time.
Use Dani's car to complete the day.
December 3, 1989
This is shorter than the previous day but some of the things you need to do aren't super-obvious. Go ahead and complain to the developer about it at @ImNotOnTwitterSoGoodLuckWithThat.
The first task is started by talking to the employee at Transistor Lodge. He will ask you to find three missing items.
One of the missing items is in the plant directly across from Transistor Lodge.
Another missing item is in the second plant from the left near the Information Desk.
Check under the bench across from Video Buffet for another missing item.
After collecting all the missing items, return to Transistor Lodge and give each of them to the store employee.
After the transition, go to Video Buffet and talk to Grunberg.
Then talk to Carol who is in the center hallway.
D.B. will now be the west hallway, Talk to him to transition characters again.
Like the previous days, Use Dani's car to advance to the next day.
December 10, 1989
This day is centered around the Secret Santa gift exchange.
Talk to Holly at the Information Desk to start the Secret Santa gift exchange.
Now talk to Jordan who is in the camping section of Fish or Cut Bait.
Next time you Talk to Holly at the Information Desk you'll be prompted to choose an envelope. Choose either one.
You now need to find a gift for whoever you chose. You can Take items from the shelves of either Video Buffet or ThoreauBooks. Give the item to Holly at the Information Desk when you're ready. The gift you give will impact whether you qualify for the Perfect Ending later on.
You guessed it, Use Dani's car to complete the day. It was around now I realized this is repetitive and started using other day-end transitions on the remaining days.
December 17, 1989
The events of the 17th revolve around trying to survive a night in the mall during a blizzard.
At the start of the day, head over to Transistor Lodge and Use the Radio to hear the weather forecast. Select WNWT when prompted for the radio station.
Then return to Video Buffet and Talk to Grunberg to advance the story.
Next go to Denim Country and Talk to Dani.
Then you need to try to exit the mall.
After that scene, enter Fish or Cut Bait to transition characters.
Go to ThoreauBooks and Use the Cooking books. I don't know why I didn't call them "cookbooks" like a normal person would.
In either order you need to visit two stores that are still open. One of them is Pogo Dawg where you need to Talk to the employee.
The other store you need to visit is Nut Shack where you also need to Talk to the employee.
Now return to Fish or Cut Bait and Give the two items you now have to Jordan behind the counter.
After the ensuing scene, leave the store to advance to the next day.
December 24, 1989
This is a tough day to describe without any plot spoilers, expect some of these descriptions to be very vague.
The events of the day start when you first enter Nut Shack.
Walk to ClothesNow and Talk to the employee there.
Next Talk to Randy at the firearms section of Fish or Cut Bait to receive an item.
After receiving the item, go back to ClothesNow and repeat the process.
Entering Video Buffet will advance the story.
Once it's nighttime, make your way to Transistor Lodge and Use the Radio. Selecting the station WVVX will trigger the next event. Bonus points for anyone who gets the radio station reference.
At the end of the all the events, exit the store to proceed to the final day.
December 31, 1989
This is a short day unless you want to try getting the Good Ending.
If you've met all the requirements for the Good Ending so far then you'll begin the day as Dani. You need to Talk to Griffy before you can leave.
Go to Denim Country to advance the story.
If you don't qualify for the Good Ending you'll start as D.B. in Video Buffet. You'll also start here after the previous scene if you do qualify for the Good Ending. Either way, Talk to Grunberg to get permission to leave the store.
Then Talk to Dani in Denim Country.
Dani will move to the Nut Shack store. Talk to her to trigger the ending. She will give you two choices. The first choice will always lead to the bad ending. The second choice will either give you more time to explore or launch one of the other endings. See the next two sections for details on how to unlock them.
Good Ending Requirements
To obtain the good ending you need to complete a trading sequence on December 31. That in turn requires Pogo Dawg to still be open. To keep Pogo Dawg in business you need to refer three customers to there.
On December 3 you need to visit ThoreauBooks as Dani and Talk to the shopper by the cookbooks.
On December 10 you need to visit the firearms section of Fish or Cut Bait as Dani and Talk to the shopper pacing around there.
On December 24 you need to visit Sunset Video as Dani and Talk to the shopper along the north wall.
On December 31 while playing as D.B. there is a trading sequence you need to complete. Again, this can only be completed if Pogo Dawg is still open. The first item in the trading sequence is found in a tent in the camping section of Fish or Cut Bait.
Give that item to Todd at Checkers.
Give the next item to Eliza at Cassette Planet.
Give the next item to Heather in the fishing section of Fish or Cut Bait.
Give the next item to Becky at ClothesNow.
Give the next item to Randy in the firearms section of Fish or Cut Bait.
Give the next item to Charles at ThoreauBooks.
Give the next item to Scott at Transistor Lodge.
Give the next item to Annette at Sunset Video.
Give the next item to Carol who is at the stand in the south hallway.
Give the next item to Griffy at Pogo Dawg.
Give the last item to Holly at the Information Desk.
Finally enter the Cavern to trigger a brief scene that will unlock the good ending. Complete the other events of December 31 and choose the second option when talking to Dani at the end.
Perfect Ending Requirements
The Perfect Ending is the Good Ending with an extra scene. So that means you first need to satisfy all the criteria for the Good Ending. There are then four other rules for reaching the Perfect Ending.
On November 24 you need to answer all the secret shopper questions positively (choose the first option for each).
During the Secret Santa exchange on December 10 you need to find a good gift. If you select the first envelope you need to Talk to Annette at Sunset Video.
There are multiple items that work, one of them is the MathHstory book.
If you select the second envelope you need to Talk to Eliza at Cassette Planet.
There are again multiple items that work, one of them is the GetAGhost book.
Giving a good gift without first talking to whoever you chose will not work. You'll know if you were successful if there's an extra scene after switching to D.B. later in the day.
During the nighttime on December 24, after using the radio you need to find a safe place to hide. Sunset Video is the only place that works.
Anytime after the Secret Santa exchange, while playing as Dani, you need to Talk to Holly at the Information Desk to get your gift.