In response to a tweet asking about gameplay for Madden 15, the Twitter account for EA Access replied, "EA Access memebers will have six gameplay hours with the full Madden NFL 15 game."
Earlier this month, EA fleshed out some lingering questions about Access on theirsupport website, saying that in "some titles you’ll be able to play one of the game's modes for a limited time, while other times you can jump right into the full game." So far, Madden 15 is the only game for which they've specified the exact amount of time that members will be able to play.
Last week, EA announced that there would be no public demo for Madden 15, and that only Access members would be able to play the game before it released. Rather than a demo however, the Access version of the game will be a full version.
As previously announced, the first five games that will be available for Early Access are: FIFA 15, Madden NFL 15, NBA Live 15, and Dragon Age: Inquisition. Games will be stored in a place called The Vault, where they will permanently stay. Currently, the games available in The Vault include FIFA 15, Madden NFL 25, Peggle 2, and Battlefield 4.
EA Access is currently available only for Xbox One - Sony having passed on the service. Monthly subscriptions cost $5 USD and yearly subscriptions are $30 USD.
Sourced Via IGN