Here is the full list of all 73 Second Chance Heroes achievements.
Kill 25,000 monsters
Kill 250 Vampires
Kill 500 Werewolves
Play a level as each character
Play as every scientist
Play as each of the less reputable Heroes
Play as each melee character
Play as every female character
Play both Caesar and Cleopatra
Beat the first level
Complete every level in the game
Complete all Bunker levels
Kill every boss
Kill W.A.R.D.
Collect 200,000 XP
Kill one of each specialty monster
Kill Mama Nibbles
Kill 25 Zombie Alien Hybrids
Kill 50 Nibbles
Kill 10,000 monsters
Kill 25 Sentient Cheeseburgers
Kill 25 Commandos
Kill The General
Kill 5 Goats
Kill 25 Fat Army Privates
Kill 5 Commandos
Kill Private Corpsepile
Kill 5 Fat Army Privates
Complete all Hobo Colony levels
Collect 100,000 XP
Kill Beelsteambub
Kill Johnny Hollowlegs
Kill The Walrus
Kill 100 Zombie Hobo Warriors
Collect 50,000 XP
Kill The Turtle
Kill 150 Karate Klutz
Kill 25 Roach Knights
Kill Zombilly
Kill Mad Mulligan
Kill a Crazy Cat Lady
Kill 5 Zombie Hobo Warriors
Kill 5,000 monsters
Complete all Mall levels
Kill The Mallrog
Open 100 chests
Collect 25,000 XP
Kill 150 Robots
Kill 50 Vampires
Kill 100 Werewolves
Open 50 chests
Collect 10,000 XP
Play as both Joan of Arc and Napoleon
Kill Dr. Neirzeit
Kill 10 Robots
Kill 5 Super Heroes
Kill 10 Body Parts
Collect 5,000 XP
Kill 1,000 monsters
Kill A Sentient Cheeseburger
Kill 5 Charlies
Kill an Amazing Head
Kill 25 Fast Food Fatties
Kill a Burglar
Kill 500 monsters
Open 10 chests
Kill 5 Vampires
Kill 20 Karate Klutz
Collect 1,000 XP
Kill a Blood Top
Kill 10 Werewolves
Kill a Giant Karate Klutz
Kill 50 monsters