I have recently learned how to do constraint processing and I figured out how to generate sudoku puzzles. I thought it would be interesting/fun to create an interactive website for these puzzles. I was planning on doing this just for fun and if I discover a way of monetizing it, that's bonus!
Anyway, I have a concern about copyright issues. WebSudoku, which has billions upon billions of sudokus apparently has them all copyright protected. Can they do this? If I am able to generate my puzzles with programs that I wrote and they happen to match puzzles on that site, am I violating the copyright protection?
Computer generated puzzles like Sudoku are not creative work and can not be covered by copyright. Thus is the prevailing opinion.
Or can they? The specific representation of the puzzle can be considered a creative process "fixed in medium" and is therefor covered. That is another opinion.
Like a patent, a copyright is only as good as someone capacity to defend it. And often dubious patents and copyrights prevent innovation and the free spread of ideas by threatening legal action.
In legal action there will be extensive conversation about whether you got the puzzle from their site- - or whether your software came up with it on its own. I hope your lawyers will pull better experts than theirs.
Your lawyer would also point out that there are lots of ways to generate sudoku puzzles. In fact here is a program someone intentionally published into the creative commons explicitly to prove this point.
So you have a choice. Clearly lots of other folks have chosen to say -- "Dude, this is so clearly in the world of open source that slapping a copyright on it is just blowing smoke." You may make a different call.
Following on from what Joseph said:
So the way to keep the proof of regeneration and head their lawyers off at the pass is to publish the seed paramaters your system uses.
Effectively publish "Game 34: P1=32, P2=56 P3=102". That way when they try to claim their game you can prove your own algorithm can reproduce that exact game ... thus your own independant work.
As for making money, you have a long attention span for users, if you can collect some type of qualifying demographics either
Once you can tell advertisers who is looking at your site for long periods of time, the right ads will start coming through to actually generate revenue.