Portal is such a fantastic concept that it would have been enough to just make another game with a lot more new puzzles. This is kind of what Portal 2 ends up being, except it switches up the aesthetics and story to give the game an altogether different feel. The gameplay is broken up a lot more between testing chambers and more "open" traversal between chambers. This works incredibly in some ways: the deep foundations of Aperture reveal colossal abandoned structures that impress upon you an overwhelming sense of the inhuman scale of this facility. Exploring these depths is mind-boggling and incredible, and really exploits the obvious utility of using a portal gun to traverse otherwise hostile and inaccessible architecture. But this taste of exploration unfortunately reinforces how restrictingly linear the game really is. Whereas in the first game that linearity was disguised by the exciting feeling of straying outside of GLaDOS' experiments, here your "behind the scenes" traversal of the facility consists mostly of being guided either by Wheatley or GLaDOS- the vast scale of the facility is always in tension with the narrow track you must follow as the player.

That being said, the puzzles are still phenomenal- tricky while rarely being frustrating or tedious. The new mechanics are fantastic, especially the gels. The moment I realized the potential of the white gel to create new surfaces of my own to attach portals to was mind-blowing. (Unfortunately this mechanic is sparsely used, as it understandably is way too open-ended)

I know it's way too ambitious and would probably never work, but part of me is so curious what a more open-world or metroidvania type structure to a Portal game might look like.