Edit History

Just spit-balling here, but what if you had zombies drop old skool gore blocks when they die like in Darkness Falls, then have those gore blocks turn into terrain blocks a few minutes later using UpgradeRated like the old "concrete drying" mechanism (pretty sure that's still a valid thing)? Then, you'd have dead bodies stacking up around your defenses that zombies could hopefully use to climb walls. I'm at work now, so can't test this out, but if you created a copy of one of the gore blocks like so:

<configs>
	<append xpath="/blocks">
		<block name="goreBlockZombieBones">
			<property name="Extends" value="goreBlockHumanBones"/>
			<property name="WaterFlow" value="permitted"/>
			<property name="Collide" value="melee,bullet,arrow,rocket"/>
			<property name="IsTerrainDecoration" value="true"/>
			<property name="Class" value="UpgradeRated"/>
			<property name="UpgradeRated.ToBlock" value="terrainFillerAdaptive"/>
			<property name="UpgradeRated.Rate" value="1000"/>
		</block>
	</append>
</configs>

Then, set your zombies so they have a have a high chance to turn into that gore block when they die:

<config>
	<append xpath="/entity_classes/entity_class[@name='zombieTemplateMale']">
		<property name="CorpseBlock" value="goreBlockZombieBones" />
		<property name="CorpseBlockChance" value="0.80" /> 
	</append>
</config>

You could play around with the numbers as far as the UpgradeRated.Rate and CorpseBlockChance go and find something that achieves the effect you're after.