If you’re bored of Solitaire or Minesweeper, I have found another way to find full version computer games.
Wikipedia actually has a list of commercial computer games released as freeware. If you take a look at the list, you will find a list of computer games released over 10 years ago.
I found downloads for games like Railroad Tycoon, Simcity, The Elder Scrolls: Arena, Wolfenstein: Enemy Territory and Star Control II.
To download the games, look for the download or developer website link under the External Links header in the individual game’s wiki entry.