Unlock the following achievements by performing the corresponding tasks:
Stunning! Requirement: Stop a vehicle with an overcharged Plasma Pistol and quickly kill the driver.
The easiest place to get this one is at the Uplift Reserve. Switch to Easy to make this Achievement a breeze. When you reach the area with the overturned warthog and ample Brutes on vehicles, grab a Plasma Pistol from a nearby Grunt and charge it up. Shoot a Brute in a cycle from close range, then approach him and melee him in the face.
My Clothes! Requirement: Plasma Pistol Overcharge and quickly kill 10 Brutes.
Unlock this one on Easy, and Kizingo Boulevard is perfect due to its high number of Brutes. Approach a Brute with a charged Plasma Pistol, then unload it on him and his armor will drop off. Quickly melee him twice (or shoot him in the head with a pistol). do this ten more times in the same level
Both Tubes Requirement: Get 10 Rocket kills on Kizingo Boulevard.
You'll begin with two rockets, and you can get a ton of kills with just these. A secret Rocket Launcher can be found behind the empty Scorpion you are directed to get into. It's lying on the ground behind a small structure. Use these four rockets to get a couple more kills.
Laser Blaster Requirement: Get 10 Spartan Laser kills on ONI Alpha Site.
This can be done on Easy. Although you start with a Spartan Laser on this level, you can get a second one in the next scene to get more kills (the area with two Wraiths and the hill). Search the top of the hill for the Spartan Laser.
I Like Fire Requirements: Kill 10 enemies with the Flamethrower on Data Hive.
This can be done on Easy. The Flamethrower is found at the end of a hallway after the icy area in the tunnels.
Naughty Naughty Requirements: Killing things that are new and different is good / Kill 10 Engineers at night in New Mombasa, alone or with another ODST.
Find a place with Engineers that spawn continuously and shoot them with charged Plasma Pistol shots for one-hit kills. You'll have to get ten all on the same level (Mombasa Streets).
Good Samaritan Requirements: Killing things that are new and different is bad / Do not kill any Engineers at night in New Mombasa, alone or with another ODST.
Don't kill a single Engineer for the entire campaign, from start to finish. If you see a count appear for the Naughty Naughty Achievement, restart the level.