Pure fun. The writing is very campy but it takes itself so seriously that you can't help but be engaged in the story, the gameplay feels surprisingly smooth even by modern standards and you have a fun arsenal to complement it. The environments are all fairly interactable, sometimes it's necessary to progress and others it can just net you some spare ammo or pills. There's also a good amount of story tidbits scattered around that you don't need to interact with, but they're usually amusing at the least. This is a game that held up very well and makes for an enjoyable playthrough.