Okay, so I got the demo of TWD and I liked it. I had 5 dollars in my wallet so I went to the Playstation store and searched for The Walking Dead EP. 3. It was there so I bought it and downloaded it. But I realized that it said ADD-ON, and I thought that I could just get EP, 3, play it, and if I liked it could buy the others. So do I need the disc? Was it a waste of money to download the episode?