Is it possible to make adventure maps and put it up to download so people who have minecraft from this person can play it?
Yes, when your map is finished go to (If you are Windows user) Start and than click Run. Type %appdata% and hit enter. You will see .minecraft map. Open it. There you will find "saves" map. Open that map. Find your map there and upload it (ZippyShare, MediaUpload, 2Shared...)
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