Newsnacho is an alternative Reddit reader that aggregates the frontpage of each of your subreddits for easy perusal. The average score of each subreddit's frontpage is used to compute the "magnitude" of each post to allow for an ordering based on their relative importance.
At this time the app only requests access to your Reddit user identity and a list of your subreddits. It won't be able to affect anything about your Reddit account.
It will take a few minutes after authentication before the frontpage of your subreddits will be fetched and available. Additionally, at this time Newsnacho will not fetch posts from private subreddits.