Originally posted by Weaver:

(Irl burials would be done this way when deep diggining wasn't practical and because the large heavy stones would deter grave robbers and animals from digging up the corpse).

But people who could move these huge stone slabs could also do more. Usually, they would cover them with smaller stones or/then earth, so as to make a true burial mound (or cairn or barrow). There are several examples in Western Europe, of varied sizes, and when they are in the state the game depicts them (3 or more slabs forming at least a table), they say that the above-mentionned coverage has been removed by pillagers, villagers (to get building materials), or erosion.