Mission 1 - Osiris: Halo 5 Guardians Guide
New to the Halo series? Don't worry about getting oriented with both the hero Master Chief and the newcomer Spartan Locke, just play the first two stages of the Mission and you'll get familiar with the faces. Let's begin with the very first mission of Halo 5 Campaign mode - Osiris.
Once the Cutscene is over, you will drop into a hot zone and take control of Spartan Locke. Being a member of Fireteam Osiris, your main objective is to retrieve Dr. Halsey from Covenant custody on a war ravaged planet. You'll jump right into the thick of battle, so get ready from some action.
Move forward and get familiar with the environment, take some enemies down. Check out some new guns like an assault rifle and Magnum pistol from the foes you've taken down. Make sure you change the guns if you run out of ammos. Keep right and you'll notice some steps in a nearby rock formation. Climb up and you'll see a doorway blocked off by some large icicles. Use your Spartan Charge to bust through this obstruction. To perform Spartan Charge Sprint towards the wall and use the right shoulder button to break it(Sprint + RB).
Keep Moving and fighting the enemies along the path. To the right hop up on a nearby ledge to jump along a set of platforms. Keep checking the HUD as it will prompt with a red signal whenever there are enemies nearby and also for the instructions on how to perform certain moves. Keep Moving on the same path to continue.
You'll see a giant door on this higher path which will take you into the Security Station. You can use this area right in the middle of everything to reach an even higher platform. On the upper platform access the terminal to analyze the Forerunner station, and wait for a door to open on the lower level. A door will open below where you need to follow to reach the next section.
Now be careful as you need to climb up a ledge from the left. Prepare to fight again with the enemies in this area. After Eliminating all move forward to Dr. Halsey's marked location(press down on the D-pad to track of her). Keep on taking these aliens down and you'll notice a large doorway along the left wall.
Once inside the doorway, run down the hall and access your D-pad to provide you with some Osiris Intel. Take a left and get ready to face off with a few Prometheans. Keep checking you D-pad to keep a track on the enemies within sight as well. Don't worry they are easy to be taken down so go ahead and Eliminate them. Head forward to the door once you're down with the Prometheans. The cutscene will trigger and end of the First Mission: Osiris.