Here is the full list of all 24 Atari Flashback Classics Vol. 1 achievements worth 1,000 gamerscore.
Eliminate all the mushrooms in a level of arcade Centipede
Win a game of Pong against the AI without losing a point to it
Reach the top of the local scoreboard in Millipede
Double your money in Black Jack ($400)
Clear a level in Canyon Bomber with limited bombs (Games 1-4)
Reach the top of the local scoreboard in Liberator
Earn a point in Pong by sending the ball into the corner when it can’t be reached
Take out the Swirl with your Zorlon Cannon in Yars’ Revenge
Reach the top of the local scoreboard in Tempest
Reach the top of the local scoreboard in Centipede
Try every game
Kill your human opponent in a 2-player game of arcade Warlords before any AIs die
Hit the ground in Lunar Lander with at least 550 downward velocity
Reach the top of the local scoreboard in Black Widow
Reach the top of the local scoreboard in Space Duel
Earn more than triple the other player’s points in a game of tethered 2-player Space Duel
Take out an entire Millipede with DDT in the arcade version
Score a kill in Combat’s Tank-Pong using a shot that has bounced at least 7 times
Get the top score of 99 in Air-Sea Battle’s Shooting Gallery
Take out 10 fleas in a row in arcade Centipede without letting one reach the bottom or losing a life
Achieve a score of 300,000 or higher in Yars’ Revenge
Earn 800 points in Lunar Lander’s COMMAND MISSION
Finish Level 81 or above in arcade Tempest without losing a life in the level
Win with no wall left in arcade Warlords