It could start with a Civil War, between the Rebels and Kompressor's army, due to terrain being removed.
The war ends in Kompressor's victory, killing, multilating all rebel blockheads, nuking the bedroom and bringing in slate.
He then betrays Badspot and turns Blockland into a dictatorship in which they capture the remaining rebel blockheads and turn them into soulless soldiers without a purpose but serving to the Lord of the Shadows.
also Rotondo went crazy and released all his mutant, horrifying creatures into the city, causing horror and fear to the civil blockheads, also a zombie mocheeze.
I've been plotting this for quite some time but I decided I'd just share it with you guys to see what you think. Also it's desorganized as forget and reminds me of Half-Life 2.