Here is the full list of all 12 Encleverment Experiment achievements worth 200 gamerscore.
Win a Multiplayer Game
Get first place for every question in a round.
Host an Xbox LIVE game
Host a Home-Made game online
Complete a Single Player Test
Master all Brain quadrants in Take-A-Test Mode
Score over 2500 in one Game Show
Beat all Marathon difficulties
Purchase all Mascots
Beat all single player opponents
Take-A-Test 5 days in a row
Earn 1,000,000 Noodles