XeNTaX

Most of modern games is copyrighted for obvious reasons, but maybe from among them is not copyrighted?

Where posible find information or table\list of these?

And how know about copyrighted game or not if game is old(for example, from 80s-90s)? And how know about it, if developer and(first situation)\or(second situation) publisher already closed?

I think if you go to sites like Home of the Underdogs, or Abandonia, you can already find a lot of games that were "abandoned". HOTU has also games there that cannot be downloaded due to copyrights. They must have some procedure in place to know that a game was abandoned. You could also ask them.

I dont think what he exactly about most\all games, because some, which was avaliable for download, was deleted links to download, because he cooperate with GOG.com.