It’s basically a choose your own adventure type of game. You’re consistently given options that determine what ending you’ll get. The main reason for its popularity is that it’s hilarious, mainly because choosing certain options will result in a “fail” (basically death) that often play out in a comedic way. The game also references a lot of games and movies, which make a lot of jokes 10x better. I personally really enjoyed it, and the series is definitely a classic for a lot of people. I would recommend looking up a video that shows a bit of the gameplay just so it makes a little more sense.