Short answers, pulled from the story.
Colossal Cave Adventure, released in 1976, is widely considered the first adventure game. It was written by William Crowther, an employee at Bolt, Beranek and Newman in Boston, and later expanded by Don Woods at the Stanford Artificial Intelligence Laboratory. The game was based on Crowther's own knowledge of the Mammoth Cave system in Kentucky.
Adventure games declined due to a combination of market saturation following the success of Myst in 1993 and the rise of first-person shooters like Doom and Half-Life. Publishers came to see adventure games as financially unfeasible, and major developers including Sierra (closed in 1999) and LucasArts stopped producing them. By the early 2000s, most commercial adventure game publication in the United States had ceased.
Myst, released in 1993 by Cyan Worlds, sold over six million copies on all platforms, holding the computer game sales record for seven years until The Sims surpassed it in 2000. It was also considered the killer app that drove mainstream adoption of CD-ROM drives, as it was one of the first games distributed solely on CD-ROM.
In 2012, Tim Schafer launched a Kickstarter campaign with a goal of $400,000 to fund an adventure game; the month-long campaign raised over $3.4 million, making it one of the largest Kickstarter projects at the time. The resulting game, Broken Age, was released in two parts in 2014 and 2015. The campaign's success signaled to developers that audiences still wanted adventure games and sparked numerous crowdfunded sequels, remakes, and spiritual successors.
Visual novels are a hybrid of text and graphical adventure games, typically featuring text-based story and interactivity aided by static or sprite-based visuals, with dialogue trees, branching storylines, and multiple endings. They make up nearly 70% of PC games released in Japan. The format has its primary origins in Japanese and other Asian video game markets.
Telltale Games' The Walking Dead series, released in 2012, won numerous game of the year awards and is credited with a revitalization of the adventure game genre. It replaced traditional puzzle-heavy design with a story and character-driven experience where on-the-spot decisions affected both the current episode and future episodes and sequels. Telltale was founded by former LucasArts employees following the cancellation of Sam and Max: Freelance Police.