I mean, I've gotten to episode 5 and I've read some stuff that talks about achievements in some of the past episodes that I didn't get. Why did it let me continue if I didn't do all the achievements? Will I have to go back and get them before I can end the game? Or is it just extra stuff that you can do or not and does not really affect the game? I guess I don't know what it means when it says achievement unlocked.