Here is the full list of all 12 Nova-111 achievements worth 1,000 gamerscore.
Kill an enemy with infighting
Exploder enemy kills multiple enemies
Play the game at 1:11am
While time-stop is active, push an enemy into a projectile
Kill 5 enemies using spikes in 1 stage
Hit two enemies with laser two turns in a row
Phase 20 times in 1 minute
Beat the game without taking damage
Bump 1000 walls
Find all secrets in the game
Collect all 111 scientists
Spend 0.5 hr in time-stop