Aegis Wing represents a very easy 180 points and can be completed in under 20 minutes.  The key to it all is getting together a group of four players as this makes the achievements easier and makes the game a lot more enjoyable.

Rookie - 5 points

Earn 30,000 points.

Easily done in solo or multi play.  The game has no scoring multipliers so just hold down that Right Trigger and plough through those enemy ships.

Veteran - 10 points

Earn 100,000 points.

Probably best with one or two players (you only share the points for boss kills) as your co-op buddies might mop up too many points.  Can be achieved on Normal difficulty.

Ace - 20 points

Earn 185,000 points.

The hardest achievement in the game (the reason it's an easy 180 out of 200).This has to be done on Insane and you'll need to get to the last level at least and take out the mid-level boss.

The best tip for this is to get another player to co-op it with you but don't let them shoot anything apart from the bosses.  They can then bail you out if you die (by collecting the resurrect ship power-up) and help you out when the action gets too hairy.

Exterminator - 15 points

Destroy all enemies in a level.

Four players on Normal difficulty should make this pretty easy.  Save the rockets power-ups for big swarms of enemies and make sure at least three players stick to one part of the screen each with the fourth sweeping around taking out strays

Untouchable - 15 points

Complete a level without taking damage.

Easy enough in single or multi.  First level on Normal, of course.  Smart use of the shield power-up will help. 

Immortal - 15 points

Complete a level without dying or losing any allies.

If you've got four players spitting out bullets, no-one should die.  Easier on level two as there is no boss battle there.

Diplomat - 15 points

Complete a level without firing.

Let the other three shoot it up.  You can even attach to one of them with the X button and ride the level out.

Halfway Point - 5 points

Finish Mission 3 on any difficulty.

Pretty self-explanatory.  You'll walk this achievement on your way to completing the game on easy. 

Epic Warrior - 10 points

Form a four-ship (Epic) formation.

As it sounds.  Worth doing for the feeling of Chuck Liddell-esque badassness it'll give you.

Teamwork - 15 points

Score 10,000 points while attached in a level.

Easier with two players.  Attach together and do a whole level.  More points are available on the later levels.

Hero - 25 points

Complete the game on Normal.

With four players this and the Legend achievement are very, very easy. 

Legend - 50 points

Complete the game on Insane.

Four players again.  Just don't clump together during boss battles or you might all get wiped out together which will end your game.