Here is the full list of all 19 Angry Video Game Nerd Adventures achievements.
Beat the game over Halloween weekend on Normal or Higher difficulty
Beat the game on "YOLO"
Beat the game on "Hard as Balls" or higher
Beat the game on "Impossible" or higher
Beat the game on "Old School" or higher
Collect 200 1ups
Die 1000 times
Kill Naggi
Beat the game on "Normal" or higher
Enter a cheat code
Find all the cameos
Find all S*** Pickles
Find Craig
Find all playable characters
Ride the Fire shark
Drink 100 beers
Kill Santa
Found Matthew Lentz
Die 100 times