Anyone ever get the platinum/all the achievements?

[HuDaFuK]

Yeah, had to resort to finding a trophy-hunting buddy for a few of the online challenges.

[predxeno]

Yeah, last I heard the mp for this game was pretty much dead.  Your best bet is to contact a boosting partner:

For PS3: http://www.playstationtrophies.org/forum/aliens-colonial-marines/188428-trophy-boosting-thread-read-first-post.html

For X360: http://www.xboxachievements.com/forum/showthread.php?t=572042

[HuDaFuK]

There's still some activity in the standard deathmatch games, but any other game mode is a ghost town.

[Corporal Hicks]

Your best bet is getting a playgroup together.

[HuDaFuK]

To clarify, all of the challenges can be completed with just one other person - the sentry guns count as enemies for the "kill two enemies with x" challenges.

[PRJ_since1990]

I did. I 100% the game on 360, then did so when the DLC dropped. Very challenging, seemingly impossible at times, especially when the player base for the MP challenges was shrinking quickly.