Each of the three Alpha Section areas shifts the style of play into a combination of puzzle solving and stealth, and for once in the history of the universe, this doesn't mean it starts to suck. Games that aren't primarily about stealth, but then suddenly switch gears and demand you creep everywhere, tend to fall apart pretty quickly. Jade's tip-toeing is instantly fun, and not painfully slow thanks to her super-slinky forward rolling. As you sneak from room to room, you're given the choice of trying to sneak past guards, or taking them out by attacking them from behind. Either comes with risks, and neither is punitive.
Perhaps the secret to the success of the game's differing approaches is the simplicity. This does occasionally lead to a muddling of the controls, with multiple options assigned to buttons, switching in and out as the circumstances require. But it also means Jade's capable of an array of different styles without your needing a third thumb. This also counts for combat, which is really nothing more than hammering a single button, and occasionally drawing on the skills of your buddy. Generally whacking at random gets the job done, but that's fine here, in a game that's far more interested in your photographing creatures than smashing their heads in.
The buddies in question are Pey'j, and later HH, a member of IRIS who works for the Alpha Section. Both muck in for fights, but more importantly can stomp hard enough to launch baddies in the air, letting Jade pull of a snazzy slo-mo smackdown, mostly used for solving combat-based puzzles. Having these two around, HH after Pey'j has tragically been kidnapped, also gives Jade someone to chat to as she progresses, and importantly, offers the interaction to reveal the depths of emotion in the game.
Pey'j's kidnapping is oddly horrifying. Jade's reaction is powerful, and provides far more incentive to move on with the story than nags or forced progression ever could. He's got to be rescued! Jade loves him!
But later in the game, when the lighthouse is destroyed and the children are missing, is the game's most masterful moment. Jade, sat on the floor of the ruined lighthouse, hugging her knees and ignoring HH's futile attempts to comfort her, is heart-wrenching. Then as HH gives up, leans against the wall and his head tips back in defeat - this is how cut-scenes are done, people. This is how they are great. And it's not the last time the game plans to pull the emotional rug from underneath you.
BG&E is a game that knows that ever-increasing difficulty, non-stop action, and incessant dangled carrots are not necessary. Just being consistently good is what matters. Being consistently good in a vivid world, with complicated and honest characters, and the most likeable lead in gaming history - that's how you become something really special. That's not to mention the wonderful score, and the superb voice acting (all apart from the Governer/photograph woman, who is eye-scrunchingly bad in an otherwise amazing cast).
Of course, it's also how you don't sell many copies. The game was never a success, despite being critically adored, and remembered fondly by very many people. That it is finally receiving a sequel still feels like a trick being played on the keen. It was always meant to be a trilogy, and anyone who's watched past the credits on the original will look at the three lonely screenshots we've seen so far and hug themselves with glee when they see the bandage on Pey'j's arm, and know that it's being faithful.
I can't recommend revisiting Hillys again enough. And despite originally playing it on the PS2, I strongly suggest getting the PC version from Steam if you can. Quite how a five year old game can run at 1680x1050 I'm not sure, but it certainly does. Quick tip: turn off anti-aliasing. At higher resolutions you don't need it, and it fixes a bug which otherwise causes texture-flashing that can make it pretty unplayable. Switched off, the game just looks fantastic.
There, made it the whole way through without declaring that I'm in love with Jade and her lovely green lips.