From Wikipedia: Abandonwareis a term used to describe computer software that is no longer sold or supported, or whose copyright ownership may be unclear for various reasons. While the term has been applied largely to older games, other classes of software (such as productivity applications or utility software) are sometimes described as such.
Here are two pieces of abandonware that are great:
1) Command and Conquer: http://forums.commandandconquer.com/jforum/posts/list/6967.page
2) Transport Tycoon: http://www.abandonia.com/en/games/240/Transport+Tycoon+Deluxe.html
Both of them are pieces of gaming history. It’s amazing to see what could be done back in those days with the limited resources that a computer could provide.
I started playing the Command and Conquer somewhere in the last year of high school. I remember how when I did that I was a big fan of the Blizzard Universe (Warcraft/Startcraft/Diablo) and Red Alert was different. It was different in that it seemed to be more appealing for multiplayer games and the variation on attack techniques seemed (at least to me at that point) so be a bit bigger than I would normally have expected from a strategy game. Overall it was a great experience and I still remember until this day some of the network matches that I played back in these days.
Transport Tycoon is a game that has a very special place in my heart. I would call it one of the greatest games that I have ever player. It was amazing. And although the game was basically an economic simulation, I would get very pumped every time I would play it and lose the track of time playing it. The Deluxe version of this was even better. The variety of tricks that you had to master in order to grow your financial empire was impressive. And also impressive was the way you had the oportunity to grow your empire and reach a point in which you would literally dominate all the map. It was amazing.