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