Here is the full list of all 25 Exp Parasite achievements worth 1,000 gamerscore.
Completed Level 2 on Hard difficulty level
Completed Level 2 on any difficulty
Completed Level 1 on Hard difficulty level
Finished level 1 on any difficulty level
Complete Level 3 on any difficulty
Complete Level 4 on any difficulty
Complete Level 5 on any difficulty
Complete Level 6 on any difficulty
Complete Level 7 on any difficulty
Complete Level 8 on any difficulty
Complete Level 9 on any difficulty
Complete Level 10 on any difficulty
Buy all upgrades
Complete Level 3 on Hard difficulty level
Complete Level 4 on Hard difficulty level
Complete Level 5 on Hard difficulty level
Complete Level 6 on Hard difficulty level
Complete Level 7 on Hard difficulty level
Complete Level 8 on Hard difficulty level
Complete Level 9 on Hard difficulty level
Complete Level 10 on Hard difficulty level
Complete any level on difficulty Normal or Hard in time and don't lost live
Complete any level on difficulty Hard and earn all 4 Nucleos in single playthrough
Fail 50 levels
Finish Level 10 with all Nucleos on Hard difficulty in single playthrough