Most video game demos simply use aspects of the game. Sometimes these demos use the first level of the game and sometimes they'll use random levels. In contrast, self-contained demos are not levels from the game itself. They use non-canon stories or side-stories to give you a feel of the game without spoilering anything or reusing a level.
Compare to Tech Demo Game.
- Half Life:
- Halo 2's demo at E3 2003 was an original level set in what became the New Mombasa levels. While the core mechanics demonstrated in it (dual wielding, vehicle hijacking, and enemy Brutes) were kept in the final game, the demo levels ran on an entirely different engine that was said to crash if the player went just the slightest Off the Rails.
- The Jedi Knight II: Jedi Outcast demo was about investigating an enemy base that had no connection to the game itself.
- Metroid Prime: Hunters had the demo Metroid Prime Hunters: First Hunt that was included in Nintendo DS packages. It has several differences with the final game notably the fact that there actually were Metroids in the demo and had a secret cutscene.
- In the demo for Lemmings 2: The Tribes, four exclusive levels are featured, one of which is similar to one of the same name in the full version, but with slight differences.
- In order to avoid spoiling the game itself, the creators of The Stanley Parable created a self-contained demo to promote it. The entirely original level contains the Narrator leading you through a tour of what is supposed to lead up to the Stanley Parable demo, but ends up becoming a surrealist nightmare. They even sent special editions of this demo to Let's Players Steam Train and Revision3 containing bits of dialogue directly addressed to them.
- Glider PRO: "Demo House" served as the playable demo as well as the game's tutorial and Attract Mode. Though included with the full game, it is entirely separate from the game's primary scenario, "Slumberland."
- Space Quest 6 had a demo with an entirely different story about the ship Roger had been transfered to being attacked by knockoffs of the Borg.
- Shenmue had a Japanese exclusive demo called What's Shenmue?, released as a preorder bonus to make up for the game's release date being postponed (the demo was released the date the game was originally going to be released) and also made available as a freebie with Famitsu. The demo features Ryo searching for Mr. Yukawa and saving him from an assaulter. It's then revealed that the entire demo was a dream made by Mr. Yukawa, which goes back to work on a marketing campaign for the Dreamcast.note
- The Awesome Adventures of Captain Spirit serves as a free prologue to Life Is Strange 2, centered around Chris Eriksen, an imaginative 9-year old boy who lives alone with his father and dreams of being a superhero named Captain Spirit. The extent to which this demo impacts the story of Life Is Strange 2 is unknown, though it has been confirmed that choices made in it as well as in the original game will affect the sequel in some way.
- Pokémon Omega Ruby and Alpha Sapphire had a downloadable demo where you played as the male lead (named "Landon" in the demo) set in Mossdeep City where you encounter Team Aqua and Team Magma. It also features the possibility to catch a Glalie (a Steelix in the Japanese version) with his Mega Stone and transfer it into the final game, where both the Pokémon and his stone are normally available only towards the end of the game's main story (or not available at all, in Steelix's case)
- Pokémon Sun and Moon had a downloadable demo where you played as the male lead (named "Sun" in the demo). It features him arriving in Alola with his mom, but it's depicted in a completely different from the actual game. In the demo Sun receives a Greninja with an exclusive ability called Battle Bond, allowing him to turn into Ash Forme after defeating an enemy Pokémonnote , and then haves to complete an Island Trial exclusive to the demo, set in Ten Carat Hill and featuring a Totem Hakamo'o. Completing the demo also allows to transfer the Greninja in the final game, alongside a bunch of items you get doing multiple subquests after completing the demo's main plot.
- The original StarCraft I demo was a campaign made of four levels that play before the events of the actual game. It was later made available as an extended version with additional missions that could be launched as a custom campaign from within the game.
- Empire Earth has tutorials that are unconnected to the game's campaigns, like Phoenician settlers or Roman soldiers.
- The demo of WarCraft 2 featured two campaigns of three levels each which were not featured in the game proper.
- The demo of WarCraft 3 was an extended version of the tutorial prologue of the actual game, featuring three extra levels. These levels were included as a bonus campaign in the Expansion pack.
- We Know the Devil has a demo which takes place shortly before the main game and serves to demonstrate the pairing mechanic and show some character moments.