In Dead Serious you play as the Lords of Decay (Nurgle would be proud!) and use your abilities to modify the geo-physical-chemical conditions in which the body rests to obtain the most interesting forms of decomposition.
At the start of the game, there are some corpses (number depends on the number of players) in a neutral state. Players take turns to modify the conditions of the enviroment (pH, oxygen or without oxygen etc) by playing cards. Some cards are only for one body, some have AoE. You could interrupt other players and destroy their work by using cards that modify conditions only on their corpses.
At the end of each turn there is a verification phase if the corpses are in the required states to be counted as refined corpses and if yes, the player gets the points for those.
The scored corpse is reduced to basic, neutral corpse again.
Refined corpses are defined by the random draw at the beginning.