Here are all the achievements for the game and the methods I used to get them. Now remember these are the methods I used and they might not work for you.

All videos, artwork and other stuff are all made by me.

The most easiest achievement you can get and probably one of the very first ones you'll immediately get. Just complete the first level

First Blood
Finish the first level

TIPS
-Can be done on any difficulty
-Can be done with friends

Butcher
Kill the enemy with the knife

TIPS
-Can be done on any level and difficulty

Bomberman
Kill 4 or more enemies with one grenade

TIPS
-Can be done on any level and difficulty
-I recommend doing it on Episode 1, Level 3 because their is a fence that allows a lot of enemies to group up together and the grenades have a very big explosion range

Spin doctor
Finish the first episode
See 'A-Gent' for NOTES and TIPS

A-Gent
Finish one episode on at least NORMAL difficulty

NOTES
- You must complete all missions (In this case Missions 01 - 05) on Normal. To be certain, reset progress and select Normal when you begin
- Completing all episodes on hard will contribute to the 'A-Gent supreme' (Complete all episodes on at least hard) but for this one you need to specifically complete the episode on NORMAL

TIPS
- Play each Mission normally and get a feel for the level and make notes on where certain objectives are so you can breeze right through
- Normal shouldn't prove difficult if you take your time, so just play it normally and be cautious
- I recommend you use Sean Shean

Wild cat
Finish the second episode
See 'Master A-Gent' for NOTES and TIPS

Master A-Gent
Finish one episode on HARD difficulty

NOTES
- To be certain you completed the episode on hard, reset progress and replay Episode 2 (Missions 06 - 10)

TIPS
- Take your time. Enemies deal more damage and most common Enemies are replaced with Generals and Soldiers who love tossing grenades. If you rush in, you will be swarmed by bullets and grenades
- Take cover. A good majority of Episode 2 has a lot of open areas, so hug the walls and hang back if there are too many enemies
- Save grenades. Only use em for Objectives and Barriers
- Focus on the mission. Complete objectives as fast as possible
- Avoid fights. if you stick to the walls, most enemies won't notice you and will ignore you, saving you health and ammo
- Skip the drama. As long as you have completed the objectives, you can just walk straight to the exit, even if enemies are firing at you

Goal scorer
Score a goal on the stadium in level 13

NOTES
- Can be done on any difficulty

TIPS
- Keep heading right and you'll see the stadium (You will have to eventually go to it as part of the objective)
- Score at either end, by pushing or shooting the soccer ball

Backstabber
Kill co-op partner

NOTES
- You must have at least 1 controller
- Can be done on any level and difficulty
- You can only use the knife. Gunfire won't damage them

TIPS
- I recommend Level 1, because the first area doesn't have any enemies which allows you to safely murder your partner

Pumpkin killer
Kill the evil pumpkin (while the Halloween lasts)!

NOTES
- You can either set your computer date to October 31st or just wait till it rolls around
- Can be done on any level and difficulty

TIPS
- You might have to wait a minute or two, as the Evil Pumpkin shows up randomly
- I recommend Level 1, because it is easy and not filled with a lot of enemies

And that's about it

-FingerRocks