The game is easy and there's so little variety that play gets boring fairly quickly. In fact the only way you can really justify the achievements as 'medium' is if you think of them as endurance trials (it took me only one very long try to get the survivor award).
 "Avant-Garde"){kind=icon}
 "Chronicles of Blood"){kind=icon}
 "Zombogrinder 2"){kind=icon}
 "Hordes and Lords"){kind=icon}
 "Coinbox Hero"){kind=icon}
 "The Next Floor"){kind=icon}