There is no doubt that there were a lot of very good video games in the 2000s, like Tom Clancy’s Ghost Squad, Call of Duty Modern Warfare 2, Gears of War, Super Mario Sunshine, New Super Mario Bros, Sonic Colors, and more. However, one popular game on the Xbox was Halo: Combat Evolved, developed by Bungie and released by Microsoft on the Xbox in 2001 and Windows PC in 2003. 

Before being contracted to Microsoft, Bungie wanted Halo to be a third-person shooter to be released for the Macintosh and Windows. Bungie even participated in the 1999 Macworld Conference & Expo. However, they were facing financial difficulties in the 2000s. Bungie contacted several companies, and eventually, they were acquired by Microsoft and got the funding to continue making Halo.

Bungie made some changes, including changing the third-person theme to a first-person shooter. They also scrapped the open-world theme because the campaign wasn’t feasible. They even scrapped multiplayer because Xbox Live wasn’t ready for it.   

After a while, on November 15, 2001, Halo Combat Evolved was released. The plot is that the Pillar of Autumn has been attacked by the Covenant, an alien race. The master chief is activated from cryo space and plans to escape into the world into the ring of Halo while battling the Covenant. The game got very good reviews and was groundbreaking. It was the first game in which you could go into a vehicle and drive around. 

It won many awards, including multiple Game of the Year awards from IGN, EGM, AIAS, etc. The game went on to sell over 4.2 million copies on the Xbox and  670,000 copies on Windows, earning Microsoft over 190 million dollars in total.