29 megabytes doesn't seem like a big deal in 2011... but when Wing Commander III came out, it was unheard of. Here was a demo that was bigger than any other game you owned. So big, in fact, that it inaugurated the previously unheard of concept of including a CD-ROM with magazines (including the first issue of PC Gamer.) The demo features an original mission, flying an Arrow against wings of Dralthi, and the gameplay itself looks a little different from the finished game. You can download it here (29 mb).