Here is the full list of all 15 SpaceDRG achievements.
Get to the menu screen
Get 250,000 Lifetime Kills
Get 100,000 Lifetime Kills
Get 500,000 Lifetime Kills
Die Once
Die 50 Times
Die 100 Times
Get a Game Score of 500,000
Get a Game Score of 1,000,000
Get a Game Score of 2,000,000
Get a Game Score of 3,000,000
Get a Game Score of 4,000,000
Get a Game Score of 5,000,000
Get a Game Score of 10,000,000
Find the Hidden Peace Ending