Here is the full list of all 18 The Seeker achievements.
Die 5 times on the same map
Pass the tutorial
Die 100 times
Travel over 1000
Disable over 50 enemies
Collect over 500
Good job... You broke the frikin game
Buy all the weapons
Disable over 150 alarms
Hack 20 terminals
Hack over 50 terminals
Complete Vallar without being damaged and triggering alarms
Complete Departure without being damaged and triggering alarm
Complete Mighty without being damaged and triggering alarm
You've healed a broken heart to get his revenge!
You just wasted 4 WATS of energy doing nothing...
You have opened over 100 tunnels!
You've explored a moon, and made a big dent in it! Congrats!