You have lived before.
In your heart are the souls of a thousand heroes. Their minds, their skills, their powers are yours to command. And their pain and their flaws are also yours to suffer.
There are those who would kill you for this gift, those who want to tear the souls out of you. With this power, they will destroy the world. Alone, you are powerless. One person cannot stop them. But you are not one person.
You are many
The setting is a modern day, urban warfare secret history affair. One day, your character is perhaps standing in a museum, and suddenly (as happens to our signature PC, Private Jack Shephard), the hieroglyphics become readable, and you discover you have lived more than one life. Hundreds, possibly thousands of lives stretch back into history behind you, and all of them are in your head.
The metaphysics is that there is a Well of Souls somewhere at the heart of creation. It wants everything to be in balance, but somehow humanity stuffed that up (to quote Gareth, it caused the universe to take on the aspect of an avocado - ie go pear shaped). In a way I'm not clear on, this caused some souls to be constantly born again and again, diminishing in power each time. Thus, a player could have a new, more powerful soul, but with less past lives, or vice versa. Eventually, you run out of reincarnations, burn out and return to the Well.
The description of the past life is up to the player, but basically any skill you might need can be potentially found there. The limiting factor is you can only draw up so many archetypes (athlete, leader, artists, thinker etc) and hope they have the skill. Also, every skill brings with it its own personality, memories and Unfinished Business. The more you let the GM design these, the more powers you can get. Your character can do research on who you were, or he can just tap in and hope the guy letting you fire a gun wasn't a psychotic murder.
Your past life can drive you mad, particularly if he has a lot of Unfinished Business. It can help a lot if you finish this business for them. Some people spend eternity re-enacting old battles, re-settling old scores, or re-courting old loves
or those who look like old loves. Sometimes you can track down the soul you knew before. Sometimes, you may never find them again. A lot of the Incarnates go mad (these are called the Lost).
With so much uncertainty, factions are hard to organise (and thus we could leave it up to the GM to decide how they worked in his campaign). The Guardians are benevolent souls who protect the Well and try to bring about an eternal society of Incarnates. The Enslavers believe that non-Incarnates should be their beasts of burden. The Immortals never return to the Well, sucking new life to sustain them from other Incarnates. Ghosts are those whose reincarnation failed to take to a new body, and Inheritors are those clever enough to ensure their new identity will benefit from their current knowledge and wealth. Finally, The Soul Police are autonomous beings controlled by the Well, keeping whatever order it sees fit to keep.
All of these factions want to control new or unaligned Incarnates, like the PCs, as well as controlling Nexus Points, where reality is closely tied to the Well. Their machinations would no doubt be the main source of plot ideas in the RPG. Outside all of these is something which seems to be destroying souls for an unknown purpose. This Soul Devourer is feared by everyone. Oh, and Houdini is a rogue Immortal who escaped death and the Well. I think.
The core mechanics involve four basic attributes - Physique, Agility, Intellect and Will, with three separate Aspects associated with each. When using a skill, you multiply the rating of the Aspect by the Skill and roll under on a d%. The past life mechanics I never really read but they involved a starting figure of 100 Resonance Points, which could be spent on however many past lives you wanted. The more you spent, the more skill points you had to spend and the higher skill levels they could have. But of course if you spent less you could have more lives. And as mentioned, the price was less if you took Unfinished Business.
There were combat rules, too, but I never saw them either. Plus notes on going insane, and an introductory adventure, and a few pieces of fiction. Finally, there was a GMs section, where it was revealed what Incarnate is truly about - how much does your past inform your present and your future? When you discover that your last ten previous lives were horrible murderers, and their minds are now yours, how do you react? You cannot just reject their desires, because if you do that, you'll never get the skills they offer. And without those skills, you'll be dead pretty damn fast because everyone is out to get you.
Past lives. Present day. Who were you, and who will you now choose to be? Find out, in INCARNATE!