Write-up: http://www.washingtonpost.com/blogs/the-switch/wp/2015/01/05/you-can-now-play-nearly-2400-ms-dos-video-games-in-your-browser/

Link to games: https://archive.org/details/softwarelibrary_msdos_games/v2

I wonder how they could do this? The WP article does not mention copyright issues. This includes premium titles of the time including Dune, Prince of Persia, Oregon Trail, Wolfenstein, etc. They are hosting the complete game to play right in the browser (see second link.)