Five whole new games has been added to the ever growing backwards compatibility library on the Xbox One. This time they all are Xbox Live Arcade games.
The new games are DIG DUG, Samurai Shodown II, & Runner2, Phantasy Star II, and Sonic & Knuckles. All the games except Runner2 are old games, with the youngest being from 1994 and the oldest, DIGDUG, is from 1982 which makes it a 34 year old game.
This isn't the first time Xbox has made old games available on Xbox One through the backwards compatibility program. They have already made King of Fighters '98, Garou, and Sonic Fighters available and it seems like Xbox will continue to make the old games from gaming history available for this generation to play on Xbox One. But Xbox has been good at mixing old games with newer ones when adding games to backwards compatibility.