The tidying up of the original game's few flaws is consistent throughout the solo experience, from splicers' urgency to run off and heal themselves when you die, to the removal of the useless inventing system.
BIG DADDY'S HOUSE
As a Big Daddy, Rapture's social system carries more depth and is more defined than during Jack's trip to town. Just like in the original game, Delta will spot Big Daddies and their escorted Little Sisters roaming the damp hallways, and if you want their sweet, sweet Adam you're going to have to defeat the even stronger guardians - which now come in rocket-hurling Rumbler varieties - in battle.
Combat, overall, is one of the sequel's strengths. Rapture, with its desperate and mutated inhabitants, feels like a more dangerous place, and multi-aggressor battles hinder our suited protagonist at every corner.
Increased toughness, bigger guns and ability to dual-wield plasmids and weapons means it's effortless for our big man to tear through gangs of baddies in tough encounters.
And with weapons like the ever-so-satisfying drill and Gatling gun - plus upgrades that make the original look simple - offloading bullets is simply a more gratifying experience than in the first game.
No better is this demonstrated than in harvesting skirmishes. Unlike before, recovered Little Sisters don't simply hand over their body-modding Adam; you have to fight to earn it. With the girl chucked safely onto your back, a quick hold of the X button forms a breadcrumb trail to the nearest, Adam-filled corpse, which kick-starts a combat sequence as you fight to protect your friend from waves of incoming bio-burglars.
You can inject tons of strategy into your harvest by laying traps and hacking nearby machinery, but it's usually far less effort (and fun) to meet every splicer visitor with the business end of your drill and a friendly ice bolt.
Gatherers' Gardens and Power to the People weapon stations offer greater rewards in the new Rapture, with maxed-out Shotguns utilising Tesla shock powers and Level Three Incinerate and Electro Bolt offering the option to charge up your shot.
Unfortunately, there's little to no variety on top of the Plasmids seen in the original game, but they're all-round less useless - even when shooting swarms of bees.
But coming back to Rapture's spruced-up ecosystem, there's a third link in the chain. Disturb the city's Little Sisters too often and one of Rapture's new monsters will come knocking at your doorstep; the powerful and ever-present Big Sisters.
Big Sisters are Little Sisters all grown up. Armed with lightning-fast reflexes and an arsenal of devastating Plasmid powers, these screeching assassins are the police officers of Rapture. Screeching, hurling flames and chinning you with a giant needle, battles with the slinky aggressors are frantic and visceral.
But strangely, even though finally defeating them is an epic struggle, overcoming the Big Sisters doesn't feel as satisfying as it should. It's obvious that at one stage the Big Sister was perhaps (or should have been) a single entity with a bigger role in BioShock 2's plot.
But as multiple, faceless aggressors, laying the killer blow on a Big Sister feels without consequence - which is totally in contrast to the depth Marin has introduced to other areas on the game.
One thing BioShock 2 does brilliantly where the original game floundered is in creating a feeling of progression and consequence to your actions. BioShock 2 constantly chucks moral decisions at you (and not just whether you should off the Little Sisters or not) and through character dialogue and the odd painful flashback it's clear what kind of path your character is treading; good, bad or somewhere in the middle, ultimately culminating in one of many different endings.