There are so many things we could do to make great, original games today that it is unreal. If you are looking for a writer to help build your world for you, let me know, i would love to help.
When i think of trolls two bits of lore come to mind, they turn to stone during they day and they are master craftsmen. With that in mind, you make a simple 'defend the castle' game in which the trolls (being master craftsmen) try to invade the castle while your standard fantasy cast (Knight, Wizard, Archer, Priest) use their various skills to defend the battlements and the gate and ultimately the throne.
Add in the modern mythology of Trolls making snide or inflammatory remarks while trying to invade said castle, if it's funny enough it should sell just fine.
As for the actual play style, i imagine it would work alot like most action platformers with the player moving the character through a series of levels set entirely inside the castle.
Or the whole thing could be played entirely from the side of the trolls, which would have it's own advantages and drawbacks.
The trolls would work like an rts game. Think something close to Plants VS Aliens, you select the type of trolls (fighters, archers, engineers, demolitions) you want to use and the war machines they might employ before the battle begins. The idea would be to conquer the kingdom and make it Troll Land or some such things. Some pithy dialogue, the right animation style, id pay 5.00 for that if looked right.
Of course you could also make Political Action Heroes. This is a fighting game reminiscent of PowerStone with the character list composed of 'stylized' versions of current and past political figures that change into super powered Political Action Heroes after collecting enough votes. So basically, Reagan(Rambo) , Bush (Fighter Pilot), Obama (Devil), Newt Gingrich (Slime Monster), Boehner (Robot), Nancy Pelosi (Witch), McCain (Zombie Cowboy), Biden (Boxer).
Hidden Characters?
Sarah Palin - Alien
Stephen Colbert - Wizard
Al Gore - Flying Head?
Finishing Moves -
Obama - Death Panels (Five old white guys sentence you to death)
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