Here is the full list of all 36 Random Heroes: Gold Edition achievements.
Unlock the Lunatic hero.
Kill a Flyer enemy.
Unlock the Gentleman hero.
Kill a Zombie Shooter enemy.
Unlock the Cop hero.
Kill a Zombie enemy.
Unlock the Trucker hero.
Unlock the Agent hero.
Unlock the Hobo hero.
Unlock the Professor hero.
Unlock the Dino hero.
Unlock the General hero.
Unlock the Hippie hero.
Unlock the Mime hero.
Unlock the Ninja hero.
Unlock the Pirate hero.
Unlock the Princess heroine.
Unlock the Punk hero.
Buy the Magnum gun.
Buy the TwinShot gun.
Buy the SMG gun.
Buy the Shotgun gun.
Buy the Plasma Pistol gun.
Find a Crystal Skull.
Kill a Zombie Runner enemy.
Kill a Zombie Turtle enemy.
Kill a Worm enemy.
Kill a BrainWorm enemy.
Kill a Red Horned enemy.
Kill a Track Shooter enemy.
Kill a Bomber enemy.
Kill a Shredder enemy.
Kill a Hopper enemy.
Defeat the Muscled Boss.
Defeat the Turtle Boss.
Defeat the Horned Boss.