Halo I–IV

Halo I–IV refers collectively to the first four mainline video game titles in the Halo franchise, developed primarily by Bungie and published by Microsoft Game Studios. This grouping highlights the initial saga focused on the character Master Chief and his conflict with the Covenant, a theocratic alliance of alien races. The titles included are:

• Halo: Combat Evolved (2001): The first game, introducing Master Chief, Cortana, and the Halo ringworld. It established the core gameplay loop of first-person shooting combined with vehicle combat.

• Halo 2 (2004): Expanded the narrative by introducing the Arbiter as a playable character, showcasing the Covenant perspective. It also introduced online multiplayer capabilities via Xbox Live.

• Halo 3 (2007): Concluded the original trilogy, resolving the Human-Covenant War and featuring a broader scale of combat environments. It included the "Forge" mode for player-created map modifications.

• Halo 4 (2012): Marked the start of the "Reclaimer Saga" and the transition of development to 343 Industries. It focused on the deepening relationship between Master Chief and Cortana and introduced a new enemy, the Prometheans.

The term "Halo I–IV" is used to differentiate these initial games from later entries in the franchise, emphasizing a specific era of storytelling and gameplay style. While subsequent Halo games continue the narrative and expand upon the universe, "Halo I–IV" signifies the core foundation of the series and its initial impact on the first-person shooter genre.