Here is the full list of all 12 WE ARE DOOMED achievements.
Complete Wave 20
Complete Wave 10
Complete Wave 30
Complete Waves 1-30
Complete Waves 1-30 with all lives intact
Collect every Trinket in the first 10 waves
Zap all the baddies in Wave 9 with a SUPERBEAM
Reach Zone 6 with 80,000 points (Endless mode)
Reach Zone 10 with 450,000 points (Endless mode)
Reach Zone 8 with all lives intact (Endless mode)
Keep a SUPERBEAM going for 10 seconds (Endless mode)
Zap 75 Perimeter baddies in a single Endless game