Here is the full list of all 21 Tachyon Project achievements.
Spend a total of 10 minutes hidden
Spend 15 seconds hidden in one go
Finish the fifth level
Finish the sixth level
Destroy 10000 enemies
Finish the fourth level
Kill 50 enemies in less than 1 second
Finish the first level
Finish the second level
Finish the third level
Destroy 500 enemies
Destroy 2500 enemies
Destroy 100 bulls
Destroy 100 Shield Bearers
Destroy 10 enemies with a single explosion
Finish the seventh level
Finish the eighth level
Finish the ninth level
Finish the tenth level
Leave a Decoy and a Turret right after
Finish a wave with less than 1 second left