Goosebumps HorrorLand is a current series by R.L. Stine, about different kids who go through scary adventures, then find themselves in HorrorLand Theme Park.
The series was originally going to be a 12-book series. The first 9 (turning out to be 10) would be about children going through scary, regular Goosebumps adventures. Then, each received a ticket to HorrorLand Theme Park, where their old foes returned. The final three (actually two) would be entirely in HorrorLand and Panic Park, and Luke and Lizzie Morris join the crew. When book 11 was released, R.L. Stine announced that he would be releasing a "Survival Guide" to describe HorrorLand, based on the online guide he had made. Right before this was released, Stine announced another 7-book arc in the series, in which characters start out in HorrorLand, receive a souveineer, return home, have a horrifying adventure with their gift, then be transported back to HorrorLand. Now Stine has announced that the series will contain at least 24 books.
In the first story arc, each book starts out with a new character(s). Characters start out going through a regular Goosebumps adventure, many featuring old foes, like Slappy and the evil camera. Then the main character(s) receive free tickets to HorrorLand, where more danger follows. Each story consisted of three parts: the actual story; "Enter HorrorLand", where the characters go to HorrorLand; and "Fear File", containing information from Luke and Lizzie. Each "Enter HorrorLand" section is continued in the next book, only from the new character's point of view. For example, at the end of book 4, Carly Beth and Sabrina run into something in the Forest, and they fear it is a werewolf, but in book 5, it describes Robby running into two girls, Carly Beth and Sabrina, explaining what really happened. Each book's characters that visit HorrorLand always run into the previous kids that arrived. In fact, sometimes the characters meet next book's characters before it's released. For example, Billy and Sheena found Matt in book 2, when his story was introduced in book 3. At the end of book 10, the characters find Luke and Lizzie, main characters of books "One Day at HorrorLand" from Goosebumps, and "Return to HorrorLand" from Goosebumps Series 2000. Then, starting at book 11, Lizzie narrates the series as they escape from HorrorLand into Panic Park, where things only get worse. The characters finally defeat the villains and escape Panic Park, but when Lizzie arrives home, she finds a dummy in her suitcase, saying that it wasn't over, and that things would get scarier.
Then, in the current second story arc, changes are made. Instead of the name of the book, Enter HorrorLand, and Fear File being the names of the sections, they become Part 1, Part 2, and Epilogue. Characters begin in HorrorLand, where they visit Chiller's gift shop and buy something. Chiller refuses their money, saying that "you'll pay me back next time you see me". Chiller attaches a small horror toy to each gift, so they can "take a little horror home with them". In Part 2, they are home, and what they bought at HorrorLand causes them to have another regular Goosebumps adventure. The problem is always solved, with a sharp twist at the end. In the epilogue, the character tries to figure out what to do about the twist, when their "little horror" starts glowing. He/she is pulled into the toy, and suddenly they are standing in Chiller House again, where Chiller says that it's time to pay for the fun they've had with their souveineer.