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 "Old School" or higher
Kill Naggi
Enter a cheat code
Find all S*** Pickles
Found Matthew Lentz
Find all the cameos
Find Craig
Beat the game on "Normal" or higher
Find all playable characters
Drink 100 beers
Die 100 times
Kill Santa
Ride the Fire shark
Die 1000 times
Collect 200 1ups
Beat the game on "Hard as Balls" or higher
Beat the game on "Impossible" or higher
Beat the game on "YOLO"