If somebody post here a game, for example, or a demo. Is there a protection considering the author copywrights ? How can he /she be sure that somebody else will not use his characters name or story or something else ?
You have copyright protection automatically on anything you publish. It is up to you to defend that in court, but to be honest, I don't think anyone has ever really ripped anyone off directly in AGS like that.
As long as you didn't steal yourself (e.g. use ripped sprites from another game), everything you publish is automatically protected by copyright.
About your second question: You can't be sure. If you don't want somebody to steal your stuff, don't publish it.
about: "If you don't want somebody to steal your stuff, don't publish it.": HA HA ! That's a good one.
That's what you get for asking stupid questions: stupid answers.
What did you expect? Some magic spell that prevents people from stealing stuff from a game they downloaded?
Since this doesn't belong in Beginner's Tech anyway, please continue this in the one you started in General Discusson (http://www.adventuregamestudio.co.uk/yabb/index.php?topic=29052.0).