The demo uses an area map similar to Junktown in the final version of the game (the map is called "JUNKDEMO" in the demo file) instead of a separate one, and it has a different plot with completely different characters, except for the dog and Phil, who have the same conundrum just as in the actual game.
The demo takes place in Scrapheap, a small town in New California dominated by two competing gangs: the Crypts and the Fools. The Crypts are led by a man named Rayze and rule the town's power generator. They are large in number and can be identified by their leather armor. Their rivals, the Fools, are led by a woman named Baka. They are fewer in number and are less formidable opponents due to their metal armor. At the time that Max Stone visits, the Fools are waiting for only one more affiliate before engaging in a war with the Crypts.
Max Stone is the only available character in the demo. While his stats and biography are the same as in the retail version of the game, his traits are different. He starts the demo with a fairly decent inventory of weapons and items, including an H&K MP9 10mm SMG, leather armor and some stimpaks.
The Fallout Demo has a main quest "Solve Scrapheap's gang problem" that can be completed in multiple ways. If the Vault Dweller decides to side with the Crypts, he can help them maintain control of the generator by helping them wipe out the Fools. If he decide to side with the Fools, he must help them wipe out the Crypts, therefore transferring the rule of the town and the generator. The player character could also just join one gang and wait for them to wipe the other gang (or themselves) out before finishing any gang survivors off, which would rid the town of all crime altogether and leave the power generator in the hands of the people. The fourth and final way to end the demo would be to doom everyone in town by using wire cutters and destroying the generator.
Though both the demo and full-release versions begin on December 5th, the characters in each version are given different deadlines to find a water chip for Vault 13. In the Fallout demo, there are 120 days to find the chip, while in the full release version of Fallout 150 days are given to meet the deadline.
- The assault rifle in the demo is named the "Colt Rifle", but was changed upon release of the retail game.
- The plasma rifle is named "Plasma Caster" in the demo, but was changed upon release, the name plasma caster was the name for the winchester p94 (original Fallout Plasma Rifle) in Fallout New Vegas.
- In the demo, regular stimpaks have the graphic of super stimpaks from the retail version, although they heal just the same super stims did not yet exist.
- Like stimpaks, a few other items had different inventory icons upon release; such as mentats, which was depicted as a needle instead of the box of pills in the retail version.
- Iguana-on-a-stick in the demo uses the graphic of iguana bits from the retail version.
- The MASTER.DAT file from the demo also contains various artwork items and some alternate interface screens for character creation from when Fallout was still A GURPS Post Nuclear Adventure.
- The interface used the GURPS system. Actually, most of the demo revolved around the GURPS system.
- When clicking on an item in the inventory screen, there is no sound.
- There are unique sounds in the demo (Gunshots, Gore deaths, Menu buttons) that are replaced by new ones in the retail version.
- In the inventory, numbers for items quantities are different than the retail game.
- Unlike the final game, many scenery objects have a very simple description.
In the game files, many unused Vault Boy images can be found, that were primary intended to illustrate the GURPS stats, but when Interplay made the decision to drop GURPS on February 12, 1997, they were kept in the demo for future use in the final version of Fallout (presumed for new perks and traits). However, they were not included in the actual game and those Vault Boy images are only present in the demo files.
- 1st row
- Area Knowledge
- Axe Mace (old image of Melee Weapons - used the same image of the final version in-game)
- 2nd row
- Bad Breath
- Bad Reputation (merge with Champion for Fallout 2 to created Savior of the Damned)
- Bad Temper
- Beam Rifle
- 3rd row
- Code of Honor
- Combat Paralysis
- Common Sense
- Computer Ops
- 4th row
- Danger Sense
- Detect lie
- 5th row
- Electronic Ops
- Fast Draw
- 6th row
- Hard Hearing
- 7th row
- Knife Throwing
- 8th row
- Luck (old image - used the same image of the final version in-game)
- No Nose
- 9th row
- Peripheral vision
- Pick Nose
- 10th row
- Sense of Duty
- Sex Appeal (old image)
- 11th row
- Sleight of hand
- Spear Throwing
- Speed Load
- Strong Will
- 12th row
- 13th row
- Weak will
- The Ambidextrious Vault Boy image was meant to be used for Small Guns, but was given to the Fast Shot trait instead. This can still be seen judging by the Vault Boy image describing skill points.
- The Sex Appeal Vault Boy of the Fallout demo is used for Strength in-game.
- The Toughness Vault Boy is used for Endurance in-game.
- Statistics that did not have a specific Vault Boy picture used the one for Level.
- Chris Taylor, in hindsight, regretted releasing the the demo because it took away time from the actual game that they could have used for both balancing the game and fixing glitches in it. He also did not think that it did a very good job of portraying the actual game.
- According to Chris Taylor, there was quite a bit of internal discussion concerning creating a demo for an RPG when they were planning for Fallout’s demo. Not many RPGs did demos at the time, and most of those that did were shareware projects, which would not have worked for Interplay. Taylor cannot remember if everybody was enthusiastic about the demo, but he thinks that they were. They just wanted people to play their game. 
- For Taylor, the most memorable part about the demo was when Brian Fargo tried it for the first time. He was killed by a hernia (critical failure on a Strength check) in the first area attempting to open the manhole cover to the sewers.
- The demo will not run properly on newer versions of Windows (including Windows XP), instead producing a black screen with an hourglass cursor, which will never finish loading. The best way to fix this is to right-click on the application (FALLDEMO.EXE), then go to Properties, Compatibility, and then under the "Compatibility mode" header, check the box to run it in compatibility mode for Windows 95. Finally, under the "Display settings" header, check the boxes to run it in 256 colors and 640 x 480 screen resolution. This will allow it to run just fine.
- ↑ https://download.cnet.com/Fallout-demo/3000-7536_4-10008318.html
- ↑ In the actual game, metal armor has a higher armor class (and therefore higher damage resistance) compared to the leather armor, but in the demo, it is reversed.
- ↑ Steve Jackson games
- ↑ Forum post by Chris Taylor, where he stated, “Personally, with the magic of hindsight, I think the Fallout 1 demo was a mistake. Looking back, I think my issue with the demo is that it took time away from the actual game we could have used for balance issues and bughunting.
I also didn't think the demo did a very good job of portraying the actual game. I have had a small measure of regret for the demo ever since we released it. (Insert "I regret nothing!" MST3k joke here!)
But if it helped sell a couple of copies... then I guess it worked. We'll never know if not releasing the demo, but having a tighter release product, would have resulted in more sales.
- ↑ Post by Chris Taylor, where he stated, “If I'm not completely senile, there was quite a bit of discussion internally about doing a demo for an RPG when we planning for the FO1 demo. Not many RPGs did demos at the time. Most of those that did were shareware projects, which wasn't going to work for us. I can't remember if everyone on the team was gung-ho for the demo, but I think they were. We just wanted people to play our game!”
- ↑ Post by Chris Taylor, where he stated, “Frankly, the most memorable part about the demo for me was when Brian Fargo played it for the first time. He was killed by a hernia (critical failure on a Strength check) in the first area trying to open the manhole cover to the sewers. Ahhh, good times...”