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