Achievement details
Description: reach 50% completion in co-op 3 skirmish missions
Time to complete: 45 minutes
Difficulty rating: 2/10
Achievement Solution:
The achievement is easy but the description can be confusing: reach 50% completion in three skirmish missions in coop. However, I tried just getting a little over 50% on three separate maps and dying enough to end the match and the cheevo didn't pop. If you're going for this (or any other skirmish cheevo) anything other than 100% seems to do no good (see EDIT below). Also the only "co-op" that counts is over Live. Couch co-op did not net me any achievements so start the hunt for boost buddy.
The object of skirmish missions is to destroy every unit on the map which is usually around 200 units. This may sound tough but its actually quite simple. Since online is dead finding a coop buddy will be your fastest route and then its all up to you.
RECOMMENDED SETTINGS:
Map: start on the default and work your way left or right
Models: Late
In the lobby when selecting aircraft make sure you're using:
Goth GO 229 and self-guided missles.
I did these after playing through the campaign and got up to 140 kills per match.
A HUGE help will be using the wingman assist buttons. If u need a repair use left on the D pad and if your coop buddy is quick enough it will completely restore your health. This can be done unlimited amount of times however it has a recharge time so keep that in mind. You do have a limited number of respawns but you should NEVER use them all unless you have never played the game before. Nevertheless unlimited repairs allows you to take some chances.
Tips:Try to conserve the enemies that give up ammo also so ur not trying to stretch ur ammo out too thin.
If you DO run out and dont have any more ammo enemies then land on a captured base (capture a base by destroying all enemies in its vicinity. A base is indicated by the airstrip logo on ur minimap) and press X to go into your menu and you can change planes, weapons, etc.
The time it takes will be determined by your's and your coop buddy's skill.
If you have killed all units and are still not at 100% make sure u have completed all stunts as they count towards the end percentage.
EDIT: getting to 50% and quitting out seemed to work for my friend so it is evidently randomly somewhat glitched. Risk playing the game twice if it doesnt unlock at 50%.
If you feel the solution is not accurate in ANY way please PM or comment below b4 voting down thanx!