I'm only going to explain the misc. things you might miss while normally playing the game. If I don't list something here, you will get it during the course of normally playing the game. Keep in mind YOU NEED TO DISABLE ALL 3 ROBOTS PEACEFULLY.

While following this guide, you can also get these achievements during this playthrough (these are not required for the "Completionist" achievement, they are just bonuses):
"Only One Quarter" (follow this guide completely without quitting the game)
"Homebody"
"Student Driver"
"OJIDCY"
"Back in Time"
"Navigational Instinct"
"Flying Ace"
"Crack Shot"
"Cartographer"
"Cyborg"
"Symbiotry of Peaceful Beings"
"Bomb Squad"
"Steady Hand"
"Cliffhanger"
"One More Thing..."

In your apartment, change your hairstyle to Agency Standard (at the bathroom mirror).

In your apartment, take a Sonic Shower.

In your apartment, use the toilet.

BONUS ACHIEVEMENT: If you also examine your washing machine and food dispenser, you will get the "Homebody" achievement. Pick up the Beverage Glass for an achievement later.

BONUS ACHIEVEMENT: If you want the "Cyborg" achievement eventually, hold E while clicking the lowest button on the food dispenser and pick up the "food".

After getting your Keycard, sit back down where you started the game and watch the INN News report.

Near the Global Transporter, use the kiosk that explains the apartment complex.

Near the Global Transporter, use the telescope.

Examine all 6 red heads in the entryway before the robots.

BONUS ACHIEVEMENT: Doing the antidote minigame without mistakes will get you the "OJIDCY" achivement.

In the room you start in, transfer Sinclair's mail to his office.

In the room you start in, examine the morphing experiment to the right of that and get Sinclair's Keycard and the Argon Canister. Use this keycard on Sinclair's office door in the first part of WSC

In Sinclair's office, examine the brochure on the table that explains the conference.

In Sinclair's office, examine the 3 entries on the computer (Smart alloys, Morphing, Time bending)

BONUS ACHIEVEMENT: Pick up the assault rifle on the wall and put it in your inventory. If you grabbed the Beverage Glass from your apartment earlier, you will eventually get the "Packrat" achievement. If you missed the Beverage Glass, get it before you beat the game.

When you get to the door you have to open with the crowbar, turn around and examine the purple map on the wall.

WSC robot GANDHI POINTS: Use filled Argon canister on the robot on the catwalk (fill it at NORAD)

Near where the robot first throws you on the ground, are small information displays on the wall. Click on one of these to enable it.

Before getting on the traincar, examine the map display on the wall straight ahead from the stairs you walk down. Make sure you do not back away from it until you can't click on it any more.

BONUS ACHIEVEMENT: For the train ride, just steer LEFT once, then don't touch it (this gets you the "Student Driver" achievement).

BONUS ACHIEVEMENT: Solving the card bomb puzzle under 88 seconds will get you the "Back in Time" achievement.

BONUS ACHIEVEMENT: If you don't miss the turn that sends you to space, you will get the "Navigational Instinct" achievement.

Mars robot GANDHI POINTS: shoot the ship until it has only one health left then use the tractor beam

BONUS ACHIEVEMENT: Doing this section without getting hit will get you the "Flying Ace" achievement.

BONUS ACHIEVEMENT: If you don't miss, you will get the "Crack Shot" achievement.

From where you start, turn left once and examine this monitor.

After leaving this room, walk down the hallway, turn left, and look at the human in the window of the door. You have to physically look through the window for the points to count (the scan doesn't count).

After completing the submarine, go back UP the elevator to what would've been the same room as the human previously mentioned. Look through this door's window and look at the typing robot.

BONUS ACHIEVEMENT: If you don't screw up the silo globe minigame, you will get the "Cartographer" achievement.

NORAD robot GANDHI POINTS: Use the claw arm and click Down, Grab, Right.

BONUS ACHIEVEMENT: You should have unlocked the "Cyborg" achievement around this point if not earlier, if you got the bonus Arthur AI biochip from your apartment at the start. If you missed Arthur, get him when you get back to Caldoria.

BONUS ACHIEVEMENT: As this point you will have triggered the requirements for the "Symbiotry of Peaceful Beings" achievement. I believe this will unlock at the end of the game if not here.

BONUS ACHIEVEMENT: Doing the bomb section under 2 minutes will get you the "Bomb Squad" achievement.

BONUS ACHIEVEMENT: You will need to either choose Bomb Squad or this achievement on your playthough. Complete the bomb section fully EXCEPT for the very last move on the very last puzzle. Wait for the timer to tick down until there is only one horizontal pixel left on the timer (each bar is 4 pixels wide). Solve the puzzle at this moment and will get you the "Cliffhanger" achievement. An image incase you are confused: http://i.imgur.com/Bktyzg8.jpg

BONUS ACHIEVEMENT: If you don't mess up the bomb game at all, you will get the "Steady Hand" achievement.

BONUS ACHIEVEMENT: After beating the game, holding E when you click Continue on the last Result screen will cause an alternative ending movie, getting you the "One More Thing..." achievement.

At this point, you should be done!