Halo 3 Full Campaign Walkthrough

Four-player co-op Legendary run of Halo 3 on MCC, completed in approximately two hours — picking up after the group's Halo 2 Anniversary walkthrough. The group plays efficiently and speed-runs most missions, collecting skulls and chasing par times throughout.

General Notes

• Halo 3 Legendary is considered the easiest of the mainline games when played with four experienced players — enemies don't meaningfully scale for the extra firepower.
• Halo 4 is considered harder due to Promethean Watchers (which intercept grenades) and the Binary Rifle.
• Par times are 15 minutes per mission for most levels. Scoring must be turned on before the mission to count toward par score achievements.
• Terminals in Halo 3 require reading all pages to unlock achievements — just activating them is not enough. All players must be present.
• Do not destroy the Phantom on early missions — it will glitch the mission if destroyed.

Sierra 117

• The Bandana Skull is available at the start — grab it for infinite ammo.
• There's an achievement for looking at the monkeys (Grunt birthday party-style easter egg up on the cliffs).
• A stationary turret near the bug/Drone section makes clearing it trivially easy.
• The brute encounter near the end is the hardest part of this mission. Removing brute helmets with gunfire exposes their heads.
• Healing brutes (in a Bubble Shield) still take damage — just overwhelm them.

Crow's Nest

• The bomb objective requires players to arm it and exit — the door sequence can be tricky with four people.
• You can skip fighting many enemies and just sprint to objectives.

Tsavo Highway

• Do not destroy the Phantom — confirmed to glitch the mission in MCC.
• Warthog driving is the focus; one gunner on the turret makes clearing the highway fast.
• Ghost choppers appear on the highway and can be hijacked.

The Storm

• The anti-air Wraith on the island must be destroyed to progress.
• You do not have to kill the Hunters in the tunnel — you can walk past them.
• The in-engine moment where the UNSC ship comes in low and its shockwave sends enemies flying is one of the most impressive set pieces in all of gaming — not a cutscene.

The Ark

• "Tank Beats Everything" achievement: Use the Scorpion tank to kill Hunters, Ghosts, and then destroy the Phantom. The NPC Marine will say the line when all three are done.
• The tank is lost after the indoor section — enjoy it while it lasts.
• Terminals on this level require all pages read for achievement credit.
• The "Used Car Salesman" achievement requires killing three enemies in a single vehicle simultaneously.
• Hornets are available in the open section; grabbing them early makes the Scarab sequence much easier.
• The Scarab fight: shooting the glowing joints/lights with missile pods brings it down. Players can board it directly.
• Two Scarabs appear near the end.

The Covenant

• Three-tower mission. Each tower must be activated in sequence.
• You can run past most waves — they do not need to be cleared to progress.
• Do not kill Johnson — he is needed for a later sequence involving the weapon.
• Guilty Spark turns on the team here and kills Johnson; this is unavoidable story progression.
• All four players must be present at terminals for the achievement to trigger.

Cortana

Set inside High Charity — heavily Flood-infested.

• This mission is widely considered the most annoying in the game due to the Gravemind voice repeatedly interrupting.
• Running ahead of enemies is the most effective strategy — Flood enemies have to transform/spawn in, so staying ahead of spawn triggers keeps the path clear.
• Grenades must be placed on specific platforms to proceed. You need at least one grenade.

Halo (Final Mission)

• Ghost/Mongoose achievement: All players must complete the final escape sequence in Ghosts or Mongooses — high lag risk in co-op.
• The par time for the Warthog run is very tight — speed run from the moment the sequence begins.
• There is a boomer-type Flood enemy near the end of the escape that can one-shot vehicles — keep moving.
• The full campaign run clocked in just over 2 hours.

Achievement Notes

• Par Times: 15 minutes per mission on most levels. Scoring must be enabled before starting the mission.
• Tank Beats Everything (The Ark): Kill Hunters, Ghosts, and Phantom with the Scorpion.
• Monkey achievement (Sierra 117): Look at / interact with all the Grunts on the cliffs.
• Skull collection: Gold skulls only count toward the main skull achievement; silver skulls do not.
• Terminal achievement: All players must be present; all pages must be read.
• Ghost/Mongoose escape (Halo): All players must finish in a Ghost or Mongoose — high lag risk in co-op.
• Legendary in under 3 hours: Achievable with four experienced players; the group finished around 2 hours.