Pitching a nearly finished game on KS is a lost cause, unless the sum is really tiny. For one, everybody will be, like, "it's almost ready, surely they can finish it without my funding".
More importantly, the kickstarter business is selling dreams:
day one, "we will deliver bestest rpg ever!11": 500000 backers
day two, "it will be isometric!": -250000 backers who wanted first person
day three, "it will be turn-based!": -125000 backers who wanted realtime
day four, "it will be fantasy!": -62500 backers who wanted science fiction
day five, "it will have a dramatic protagonist with unique npcs!": -31250 backers who wanted blank state party creation
day six, "it will have skills developing from use!": -15625 backers who wanted xp and levels
day seven, "it will have mana!": -7812 backers who wanted memorization casting
...
day 30, "it will have blue interface buttons!": -1 backer who wanted green interface buttons.
the more specific you are, the more people perceive it as not being their dream game. vague pitches sell best, as long as you have a celebrity to back them up.