Full list of all 56 Game Room achievements worth 1,000 gamerscore. It takes around 60-80 hours to unlock all of the achievements on Xbox 360.
Filled a Room in your arcade
Placed 5 arcade Decorations in your arcade
Placed 1 Decoration in your arcade
Placed a Theme in your arcade
Visited the Showcase Arcade
Place 5 unique Themes in your arcade
Theme an entire arcade with unique Themes
Activate a Mascot in your arcade
Place a Game Cabinet in your arcade
Visit a Friend's arcade
Play a Friend's Game Cabinet
Win a Challenge
Send a Challenge
Win 10 Challenges
Win 20 Challenges
Beat your own High Score in a game
Play a game for 1 hour continuously
Spend 4 hours total playing games in your arcade
Spend 8 hours total playing games in your arcade
Spend 16 hours total playing games in your arcade
Spend 24 hours total playing games in your arcade
Spend 36 hours total playing games in your arcade
Win your first Medal
Win a Medal of each Type (Point Buster, Survivalist, Time Spender)
Win 2 Medals of each type (2x Point Buster, 2x Survivalist, 2x Time Spender)
Win 3 Medals
Win 6 Medals
Win 9 Medals
Win 12 Medals
Win 15 Medals
Win 18 Medals
Win 21 Medals
Win 24 Medals
Win 27 Medals
Win 30 Medals
Win 33 Medals
Win 36 Medals
Win 39 Medals
Win 42 Medals
Win 45 Medals
Win 48 Medals
Reach Level 2
Reach Level 5
Reach Level 8
Reach Level 11
Reach Level 14
Reach Level 17
Reach Level 20
Win 10 Medals of each type
Win 20 Medals of each type
Win 5 Point Buster Medals
Win 10 Point Buster Medals
Win 5 Survivalist Medals
Win 10 Survivalist Medals
Win 5 Time Spender Medals
Win 10 Time Spender Medals