Making the story's change in tone feel natural

Question

I am writing an epic fantasy story for a videogame I will make in the future. In the first half, it has a lot of edgy and dark humor, but the tone feels arcadey when it comes to killing random npcs.

Halfway through the story, it ends up becoming more serious. There is still some of the original dark humor and tones, but they are not as much present, and the characters act more serious. For extra detail:

• This change in tone occurs when the deutertagonist's love interest is brutally killed, and the group actually sees a battlefield for the first time (prior, it was just mainly small groups mercenaries, but the main army is WAY larger, and more violent and ruthless.)
• The killings of NPCs are a bit longer, but with some elements to make you feel a bit bad (begging for mercy, not much fighting music, etc.) There are still some times where one can kill many NPCs like it is nothing, but most of the time, it feels like you are actually killing people.
• The game does not congratulate you for much killing. It does not really bash you for it, but it does not make you feel like you achieved anything either (with the exceptions of enemies and most bosses, and this is mainly for passive and neutral NPCs.)
• The main characters act more mature and serious. They don't completely change, and will sometimes joke around, but will take quests more seriously.

Aside from these, what are ways I could have the story's tone change, but have it feel natural and not forced for the sake of being edgy?

Answer 1

A few ideas, YMMV:

1. Foreshadow. Set a few hints or pieces of dialogue early that will not only clue your reader in on the tone, but also help them tie that realization back to an earlier part of the story. An "aha!" moment for the reader, just as much as for the characters.
2. Character Arc. If your main characters don't grow, then any growth that occurs in the story is unlikely to be a main theme, especially in a video game, where you don't have the benefit of extensive time spent with the characters; episodic storytelling (e.g. cut scenes/FMV) has to be more concise than do novels.
3. Thematic Consistency. Your point about not rewarding the player for kills is intriguing, but you create exceptions, which mitigates its impact. Keeping a much harder line on what you reward the players for will help to underscore the theme. If you do reward for defeating a particular foe, make sure that the why of it adheres to your theme.
4. Rooster to Roost. An "Oh. Damn." moment, when the characters gain clarity, kinda to Phil's point in comment. But it can't just be the character who says "oh damn." Your reader should say it too. It's that moment when the character(s) deed backfires or reflects back at them; or that moment when they go so impossibly, irredeemably far over the line that you're left breathless by the horror of it; either as Turning Point or as Nadir.
5. Gamify it. What if you put it on the player to make it happen? I'm kinda brainstorming out loud here, but as a gamer, it would be fascinating if the next unlock I'm grinding for is (perhaps unknowingly) contingent on the character(s) growth arc. Perhaps similar to the choose your own path of Witcher dialogue/decisions, but what if it were somehow incorporated into actual game play? Like choosing to capture or neutralize a boss, potentially more difficult accomplishment, rather than stab all their HP away? idk Just a noddle....