I'd like a new Kotor game, with Force Unleashed like motion cap animations for all the Jedi.
-An truly EPIC storyline*, massive battlegrounds with hundreds of AI npc's fighting each other.
-Mass Effect engine (or higher), with Mass Effect feel.
-In-game visions of the future (being the one who makes the Son of the suns prophecy)
-10 years after Kotor 2, first newly trained Jedi. Quit powerful, ex-padawan in the time of Kotor 1. Too young to have been a target in Kotor 2.
Go around the galaxy doing Jedi stuff. No-one expects the Jedi to be back, so the 'ZOMG I ROCK' feeling is there when you sever a thugs gun in half with your lightsaber.
-Join the Republic in a (standard) war and become the first Jedi since the Exile to actually lead armies.
-Be the star of the rebuild Jedi Order, like Luke is, or destroy it.
-Ending: find out about Revan, join him and the Exile in the unknown regions on a barren, rocky planet to make one final stand against the Sith there. Incredible battle, forcing the Sith to wait another 300 years before they invade (Kotor MMO)
-In short: Be THE hero.
-Fatalities. Cut someone's hand, head or will you let him/her live?
-Style. You should be capable of choosing your own fighting style, out of all the lightsaber forms.
-Force powers; between Force Unleashed and Kotor 2.
-Semi-destroyable environment. Think some Mass Effect once more.
-Soundtrack. I want John Williams.
Yes, I have thought about this.