I would like to have the ability to link one game to another, passing some parameters along the way. This would give the ability of chapters without having to make one giant book. Also, you could assure that the player finished one chapter/level/test before advancing to the next.

One way to do it: Put an encrypted disk file in the Quest directory. When the game starts, see if the file exists. If it does not, either let the game proceed as a new game, or display a message that the player must complete the previous step before proceeding, then close. If it does exist, use player name, accumulated scores, or other parameters to proceed.

Another nice feature would be the ability to output data to a disk file. Accumulated scores, progress reports, even troubleshooting info could be captured this way.