Gamerscore Milestone : 400 GS

I’ve just reached 415 Gamerscore Achievement points!

The achievement which tipped me over the 400 GS milestone was:

Date: 21st Dec 2009
Game: Defense Grid
Platform: Xbox360 (Xbox Live Arcade)
Achievement: Field Promotion
Description: Earn at least one silver medal in any mission after The Awakening
GS Points: 10