Become a recruit of the Imperial Navy under the command of Darth Vader, and pilot space vehicles that will leave you breathless.
The demo-release of "Star Wars: TIE Fighter", which was released in January 1994, features an exclusive mission, which was not part of any of the full releases.
At the beginning, the demo starts a screenshot-slideshow of an alternate version of the TIE-logo as well as the intro and the concourse with many details different from the full release.
The second part includes a quick briefing by the flight officer.
The third part is a 45 minutes long mission (let's call it "Strike at Remitik"), in which the objective is to destroy a Rebel repair yard as well as ambushing Rebel ships escaping from the Echo Base on Hoth. After these objectives are met, you can prove yourself against (Top) Ace A-Wings of Rogue Squadron armed with missiles.
Like the screenshots shown in the slideshow, you can spot many differences to the full release during the mission as well. The TIE Fighter cockpit is a completely different one, which looks similar to the TIE Bomber's of the full release. The CMD is basically a hybrid of X-Wing's and TIE Fighter's. The wingmen's voices, the sound effects as well as the iMuse soundtrack are still the ones from X-Wing.
More info can be found at MobyGames.
A quick gameplay video of the demo, courtesy of swaaye: