I've been wondering...How important are those copyright agreements you have to accept when you install a game? Would a person be able to sell my game without my permission if I don't include it? Or do some other evil stuff?
In accordance with the "Berne Convention" you do not actively have to claim your copyright anymore. The creator of a literary and artistic work (software is considered literary work) will always hold the copyright to his or hers creation.
If you are considering whether you should write (c) copyright on your software. I will recommend you to do so, since it establishes with certainty, that you do wish to uphold the copyright. BUT as said, it would still be illegal for someone to copy your work if you do not write this.
The user agreements does not have an effect on copyright validity. A game is still copyrighted even if you don't accept the agreement or the game doesn't have one.
The purpose of a user agreement is to restrict the user from doing stuff that isn't defined by law, for example only install the software on a single computer, or prohibit the modification of software, as well as limit the company's liabilities of damage caused by the software.
- Ok, you must admit that was the most creative cussing this site have ever seen -
Also, in the unlikely event of a court case in regards to copyright you can always send yourself a copy of your own game (with a note of your name and details) before you release it publically (recorded delivery if possible). Don't open it, the timestamp will prove that you are the originator of the game.