The Xbox 360 has had over 2,000 games released for the platform as of January 2018. This means that roughly 25% of the entire Xbox 360 library is now playable on Xbox One. Of these 538 backwards compatible titles, over half of them are Xbox Live Arcade games. MauroNL also calculated that 37% of the entire XBLA library is now backwards compatible.
Only 33 Original Xbox games are backwards compatible. This is only a sliver of the entire library, adding up to only 3% of the whole 1,047 games that make up Original Xbox library.
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