I have a shakey idea for a game, and I need help fleshing out what mechanics could make this work.
I want to make a game that, on the surface, is a fun little exploration/dungeon crawler/rpg-lite sort of game. There's some story, a large map, and basic quests to go off to various dungeons and defeat all the monsters that are threatening the kingdom.
The idea is that a player can play through, and defeat the game by just going and defeating the monsters everywhere, and that should be a rewarding enough way to play the game.
However, I don't want that to be the only way to play the game. What if the monsters attacking the kingdom from a nearby "dungeon" are just misunderstood, or are being provoked? What if they could instead be made into allies?
For each set of set of monsters threatening the kingdom, I want the player to either be able to just go and kill them all, or find some other solution, but for killing all the monsters to be the only obvious thing to do.
The idea being that finding a different solution should feel very rewarding, or a suggestion that there are other solutions should come late in the game and provide motivation for the player to replay the game.
My question is: What sort of game mechanics could be used to provide an alternative way of progressing through the game while not making it obvious that the alternative exists? I think if a dialog tree open up with the first monster you met in each dungeon, it would telegraph the idea that there's an alternative solution. So how could there be a dungeon of monsters that you can wade into and immediately start fighting, while at the same time there being a non-violent solution?