Ok now I have found where I put the file that I unzipped. I can't run the program because it says that I am missing files or another error. Shareware, freeware, demos and adware are free for download.
Demos are small versions of the full game.
Usually demos are the first map of the full game. They are meant to give you an idea of what to expect in the full version. Shareware is a full version game that lets you try it out and usually prompts you at a later time to buy it. If you like a particular sharware game, we encourage you to purchase it. The author has to make a living too.