Game Idea: To get stronger, you have to take the power of you allies (power transfer)
The mechanics are simple. For your main character to get stronger, e.g. better stats, higher level, more weapons or abilities, your allies in combat have to get weaker. You start with a level 1 sack of potatoes with little ability of his own but is accompanied by one or two bad ass no-McGuffin types. As you play through the game, the player gets chances to steal the powers of his allies to make himself stronger. You can balance this out by requiring the use of each character throughout the game, so you have choice of power-transfer but you make parts of the game harder for yourself.
Because of the element of selective power-transfer, this leads to an opportunity of a different kind of pick your character’s story for the game. If you choose to keep your new recruit as a level 1 sheep herder, then your play style has to be one of meticulous care , since he can’t just go about slaying enemies with a fling of a sword, throw of a fist. This means that the two allies area always going to be the ones poking fun at how weak he is and relying on dodge tactics instead of jumping into the fray like they do.
Suppose you try to balance it out then. Have everyone’s power’s relatively the same. Then you can have a story of acceptance into the group where everyone can be as equals, but always have the fear that the main character will choose to drain their powers until he’s too powerful.
Or, we go with a complete power-transfer and the roles have reversed. The characteristics that made the allies powerful to work with are now faded and the main character embodies all of these traits. Strength, courage, agility, intelligence. Whichever traits used to make your allies badasses are completely transfer to the main character.
Coupled with Morality
Couple this with a morality system and you can have interesting different archetypes evolve from your main character. The weak super villain always living in the shadow of his much stronger compatriots. The gang of heroic idols who all share a common goal. Many other combinations depending on both the characteristics that you built + morality that you choose.
This can fit an RPG setting, though would seem a bit too boring. Maybe an action or action RPG setting like a Devil May Cry, Rouge Knight/Castlevania or Dark Souls-type game. A game where you’re forced into playing between the main character and the allies in isolated situations making your choice of balancing power-transfer meaningful.
In parts of the game where all the characters are together, there are opportunities to power-transfer. You can either be conniving and take it without asking or ask upfront, which could work out into the morality system. You probably shouldn’t be able to take all of their powers at once, but make it so you have the ability to take more power later on.
Giving power back would be an interesting choice in morality as well. You find people along the way that are too weak to do things on their own, but they plan to do good or do bad. You can give some of you power to them, making you directly weaker but possibly benefiting you in the future.
Other game ideas can be found HERE