Found this list on the epic forums guys, check it out if you get a chance it tells you how to recieve weapon skins in gears 3 from completing gears 1 and 2 achievements, even something in there for us Gears PC players. Here's the video where we got the info.
http://www.twitch.tv/epicgamesincAnnouncement 1:
Gears of war - Domination achievement - Complete 10 Chapters as Dominic Santiago in campaign on any difficulty - Chrome Retro Lancer
Gears of war - Don't HATE the Player achievement - Finish the match with the highest points in a Ranked Match - Chrome Lancer
Gears of war 2 - Dirty, Dirty Horde achievement - Complete the first 10 Waves of Horde Mode - Chrome Hammerburst
Chrome Gnasher - Complete all Campaigns
PC Legacy Unlock - Chrome Sawed Off
Announcement 2:
Onyx Medal Unlock = Shiny black, Onyx skin. 6000 kills with Gnasher = Onyx skin. 3000 kills with Hammerburst and 3000 kills with Gnasher = nothing.
Announcement 3:
Level 100 Gears 3 - Golden Omen skin?
Questions Answered:
Can you use Mutators in Private Matches - No - (NOOOOO Dammit )
Does the Veteran Gear achievement need a timestamp? - No
What will be the rarest skin? - Golden Omen
Will the Season Pass be available at 12:01 - Yes
How long will the Season Pass be available - Forever
What are the starting default characters? - COG - Marcus, Dom, Anya, Cole and Baird - Locust - Savage Grenadier - Savage Drone - Myrrah - Drone - Sniper
If one person dies in 4 player camapaign does it affect everyone else - Story Mode - Yes (No man left behind) - Arcade Mode - No (Person respawns when battle is finished
Do Planted or dropped Boomshields disappear between rounds? - Yes
How many Grenades can be planted or held I'm not sure in Horde - 2 for all
How many Silverbacks can be used during Horde - 2
How many Medals were added after the beta - Several Ribbons, name changes on Medals. Rewards are changed
Are there any plans for Gears of war 3 EXP events - Lot's of crazy stuff. Turn on Mutators. Everything will be on the calendar.
THAT'S ALL FOLKS
Calendar