Just try typing 'old games' or 'classic games' into google, or any search engine. Most of the games before '95 would be DOS based. I have a few CD Roms from the old Computer Gaming magazine with a bunch of Demo's they would pack with each monthly release of the magazine. The Dates on the CDs are 1996.
Here are some old demo, shareware games you can try.
http://ftp.hs-niederrhein.de/~ftp/pcgaac.htm
Just go through each dir, and click on the INDEX to view the descriptions.
http://ftp.fh-niederrhein.de/~ftp/pub/dos/games/
Not sure if these are old, but you can skim through em
http://www.pcgamer.com/eyewitness/eyewitne...2003-03-26.html