every seconds:
loop all entities:
if loop-entity is a zombie:
loop all entities in radius 2 of loop-entity-1:
if loop-entity-2 is a chicken:
make loop-entity-1 pathfind to loop-entity-2 with speed 1
if distance between loop-entity-1 and loop-entity-2 is less than 3:
chance of 40%:
damage loop-entity-2 by random number between 0.3 and 1.5 hearts