Halo: Combat Evolved/Keyes

Master Chief enters the Truth and Reconciliation by Halo's teleportation system. After a quick reorientation, Chief is ready to search for captain Keyes.

Keyes
After arriving, walk down the corridor. There is only one possible path, which will eventually lead to a broken floor with leaking coolant. You will have to jump down the hole into the water below, as waiting will only spawn endless waves of flood.

On Halo's surface, there will be Covenant and Flood forces fighting among themselves. In general, you will want for them to finish fighting first, then either clean up the survivors or move past them undetected. The first section simply has Elites and Flood fighting, and additional Flood arriving from the coolant.

The second battle area has a few covenant behind shield walls. When the battle calms down, head straight ahead into the cavern, attacking only those that pursue. The canyon ahead contains a large number of flood before reaching an overlook of a battlefield between Covenant and Flood.

You can wait outside the third battlefield to let the waves of flood soften the covenant, and jump in at any time. Jumping in will stop the flood reinforcement in the local area, and if you can defeat all enemies, you will get a checkpoint when you approach the next area.

You will come across a gun turret. Approach and hide to have the flood approach the turret. While the two opponents are distracted, run past the enemies by diving into the water, and circling around the bend. Continue along the path and keep moving forward without stopping until you reach the checkpoint.

In the last section, keep running until you see the lift. On the ground to the right of the lift is an overshield, which you can use to help defend against the approaching enemies as you reach the lift. Once you reach it, hold out until the cutscene activates and transports you into the ship.

Upstairs, Downstairs
One of the doors is open, leading to a few corridors. The corridors will initially contain a few enemies, before reaching a large room. You should snipe the carrier forms below, as they will likely cause problems when you proceed through the next door.

In the next door, you will head down some ramps, but there is continuous reinforcements approaching from the ceiling. You will first have to run past the ceiling, and turn the first corner. Hold off against the enemies chasing you, while watching for new enemies approaching from the doors at the bottom of the ramp. If possible, you may want to manually save a checkpoint.

The large room will have a few enemies, and an overshield, but nothing of a significant threat if you pre-cleared the enemies. The exit corridor leads further down the ship, eventually reaching a hole. You can throw a grenade down to soften the enemies clustering below before jumping down. Around the corner is a flood-covenant battle. Defeat the enemies that are in your way. When you get close to the hangar, enemy flood will approach from behind, requiring you to move forward when you see new dots on the radar.

In the hangar, the first door on the left is a dead end, that contains two hunters. Instead, take the door in the other corner to reach the third level of the hangar. There is a large swarm of flood that advances from the captain's location, with a small final battle just outside the bridge.

The Captain
Kill all enemies and reach the captain on the bridge - in the cutscene, you'll see that he was transformed(oh no).

After the cutscene, both flood and covenant arrive. Take cover from the battle, and return the way you came to the hangar.

At the hanger, you can down a floor by taking damage to about half of your shields. You should do so only if it is safe, but can use it as a very quick route to reach the Banshee you need to escape.