If you didn't fall for the Modern Warfare Remastered hype, or you simply want to reexamine Call of Duty 4: Modern Warfare unchanged, you can do so now on Xbox One.
The Xbox 360 version of Call of Duty 4: Modern Warfare is now playable on Xbox One thanks to backward compatibility.
Like all previous backward compatibility releases, this means that you can pop your disc in (if you still have it) and Xbox One will automatically download the latest version. Alternatively, you can buy the game through the store, where it's currently being sold for $17/$15 for Gold.
Both single-player and multiplayer should work, and you may even get a frame-rate improvements or a graphics boost if you're on Xbox One X - though Microsoft has not explicitly stated such improvements have been made.
— ? Larry Hryb (@majornelson) March 29, 2018
The arrival of Call of Duty 4 means only its sequels, Modern Warfare 2, and Modern Warfare 3 are the two games missing from backwards compatibility.
Call of Duty 4: Modern Warfare was released in 2007 to critical acclaim and impressive sales. It's considered one of the best games in the series, and is credited with kick-starting a surge of modern military shooters, and RPG-like perks in competitive shooters. Both of which would go on define the past console generation.
If you'd like to check out the remaster, Modern Warfare Remastered is currently on sale in the Xbox One Spring sale for 30%-40% off.