Here is the full list of all 26 N-GON achievements.
Kill 1500 Enemies Total
Kill 3500 Enemies Total
Kill 8000 Enemies Total
Gain 75000 Score Total
Gain 200000 Score Total
Gain 500000 Score Total
Travel 5 Gates in one run
Travel 10 Gates in one run
Travel 20 Gates in one run
Gain 9000 points in one run
Gain 16000 points in one run
Gain 25000 points in one run
Kill 250 enemies in one run
Kill 750 enemies in one run
Kill 1500 enemies in one run
Clear 15 waves in a row
Clear 25 waves in a row
Clear 50 waves in a row
Die 10 Times
Glad you're having fun
Travel Past 15th Gate
Travel Past 30th Gate
Travel Past 45th Gate
Travel past 50th Gate
Go past 3rd gate in Endless Mode
Go past 5th gate in Endless Mode