Halo 3/Sierra 117

Halo 3 begins with a really small tutorial mission which is called 'Arrival' which helps set your controller's aim to normal or inverted. It also contributes some of the story to Halo 3 so WATCH it if you want to know what’s going on. After that you'll get to the first mission!

Sierra 117

 * Primary Weapon: Assault Rifle
 * Secondary Weapon: Pistol
 * Recommended Skulls Activated: Black Eye, Thunderstorm, Famine and Tough Luck

Walk it off
At first you'll realize that the assault rifle Johnson gave you isn't in your hands. Don't panic, it'll appear in your hands once you went near to the arbiter. Then 1st time players will want to test their Spartan powers first by overtaking the marines and realizing you can easily jump to platforms while they have to climb. You will also get an objective: Get to the River for evac. Where's the river? Don't worry, the marines and the Arbiter will lead you to it. Follow the narrow canyon like path and you'll find an open area with a nice little waterfall. Look left where the log is and jump over it.

After jumping, you'll hear a captain brute say, “Spread out you grunts, find them!" that’s because they also saw you crash here but Johnson found you first so too bad! Now kill the grunts first if you are playing on legendary or turned on the Catch skull because grunts just simply LOVE to throw plasma grenades and if you kill the brute leading them before killing them one of them will stick two or three plasma grenades on themselves and scream gibberish or "KAMIKAZE!!!" and charge towards you and with you trying to kill the more important enemies, you won't probably notice the insane grunt exploding in front of you and with the Iron skull activated, you simply won't like that.