Darker and Edgier

4 vs. Satan:
*The second half. The first five were more nasty jerks, while the stronger five are nastier and all-powerful as well.
Alex in Princess Quest:
*The first part has some vaguely comedic moments, not so the later part.
The Stone of Power:
*The second part, the first has a bunch to find the titular stone to Take Over the World, the second has a mass-murdering dragon a main antagonist.
The Three Kingdoms
* NONE
Dragondawn
*Act 3: The first cases are theft. This one is a murder and a pretty vile one, too.
*Act 5: In spades. It starts with mass murders, then the headquarters are destroyed and some important characters killed and then the world is at risk.
Harter Knall
*The first scenes with the main duo are funny, but once Greylands deeds begin to show, things become serious again and it only gets worse from then on. Until the climax, that is.
Hero Story
*NONE
Kill the Demons
*NONE
Satan Saga
*The part introducing Trianuk. Not only does it feature a betrayal, it starts to feature mass murders committed by almost any character who aren't the main characters.
Story of Hero:
*NONE
The Legend of Devils
*NONE
The Sidestory Duology:
*2: Downplayed. The first part is mostly a joke, the second features some humour, but less frequently.
The Time Of Bloody Fear:
*3. While the first game isn't lighthearted, it still leaves most characters alive, this one in the second arc has Eldon killed at the start and then towns get destroyed and other seemingly important characters are killed.