Demo

A demo, a shortened term for "demonstration", is a special playable teaser for a video game distributed digitally to players to give them a chance to try a game before they buy it. Developers may also bring demos to conventions in order to promote and garner interest in the game. Prior to the popularization of digital downloads, demos were distributed through "demo discs" either to other retailers or as bonuses in gaming magazines. Demos typically would be a largely complete version of a game, but some contained content that was changed or removed entirely. Generally, a demo of a game has many features limited or removed entirely, but some will contain the full game and block it off with the use of a timer or other means.

Super Smash Bros. Melee
In Japan, two demo discs were distributed for Super Smash Bros. Melee. One was a standard demo disc and the other was a special event disc that was used for unknown purposes. Unlike the standard disc, the event disc limited players to only 2, 3, or 5 minute matches and four players were required in order to play. While not much information on these discs exist online, most claims are generally in agreement that the discs are just the final build of Melee on a different disc. On the standard demo disc, all unlockable characters are unavailable and cannot be unlocked.

In America and Europe, a demo for Melee was available alongside other games and previews through the March 2002 edition of the Interactive Multi-Game Demo Disk for GameCube kiosks at several retailers. The disc also included a movie of the game that served as a preview. The demo was restricted to one battle per play.

Super Smash Bros. Brawl
The first playable demo for Brawl was showcased at the first E for All event in 2007 and featured 14 of the characters, 15 counting. The demo revealed many things to fans that were either briefly touched upon by the or wasn't revealed at all, and was heavily documented by  in one of the largest SmashBoards threads to date.

Another playable demo was featured at the. Versus mode and The Subspace Emissary were confirmed to be accessible in the demo. As no known recordings, photos, nor text have surfaced about this demo, further details about it, including playable characters, are unknown.

Super Smash Bros. 4
A demo of was made available on the Japanese eShop on September 9th, 2014 and September 19th, 2014 in other countries. Additionally, download codes were distributed to select members of Club Nintendo Europe and Platinum members of the United States Club Nintendo on September 12th, 2014. The demo is restricted to Vs. Mode and is the only playable stage. Rules are set to two minute time matches and cannot be changed. The only mode accessible is the Tips section. The eShop version is limited to 30 plays, whereas the Club Nintendo version has unlimited plays. A Smash Run-focused demo was also showcased at events including Smash-Fest and another demo was showcased at E3 2014.

did not have a public demo release on the eShop, but a demo build of the game that was used for was playable at events including E3 2014 and Smash-Fest. Due to the number of demos released, the game underwent several changes before the final build.

Super Smash Bros. Ultimate
A demo for Ultimate was never released on the eShop, but a demo build was heavily publicized throughout the world for various events up until its release, starting with E3 2018. Notably, Nintendo granted permission to bring the event-only demo to the house of Chris Taylor, a 21-year old Super Smash Bros. fan who had terminal cancer, in order to make his dying wish come true.

Trivia

 * While a demo build for Super Smash Bros. was never officially released, unused text in implies that the game was meant to appear as a Masterpiece, but was ultimately scrapped.
 * ,, , and are the only four characters that appear in all three Super Smash Bros. 4 demos.
 * is the only character prior to Ultimate to appear in a demo of a game but be unlockable in the final product.