There are a bunch of resources at your disposal!
The easiest one is to watch the Kickstarter Live stream from March 6th. The Manifest Team plays a quick session of Manifest and then answers a bunch of questions during the Q&A session.
Also the Essential NPCs Podcast did 21 actual play episodes of Manifest. They also have a segment at the beginning of every episode where they talk about many of the gameplay mechanics of Manifest!
You can also tune into our upcoming countdown livestream on April 1! There we'll be taking your questions, playing some Manifest, and also going through a few tutorials of how to play the game!
At first glance the Fistful of D20s system may seem intimidating, however once the players have a grasp of the basic dice mechanics, it really does bolster the narrative RPG experience. Go check out all of these resources, they are a great way to get a feel for Manifest and also it's game engine.