Novel. Computer game company where male character returns to solve bug. He was in a 4 person team that created the first game during summer camp.

[Mia]

novel: main character called in to old game company
He was in 4 person group that made the first game during a summer camp but later withdrew. Ends up playing all the companys games to solve a puzzle the founder left

[Kris]

Mia, what's the genre (which we need to add to the header/ topic title) - e.g., science fiction for teens adults, thriller, mystery, etc.? How old is the main character?

What type of computer game?

Around what year did you read this book?

I added a few details to the header. Feel free to edit it.