I tell a lie - one of the bigger changes between this revised version and the original Hydrophobia is Prophecy's final level, where Kate finally gets the chance to push the water around a bit. This section is both underwhelming and extremely short.
At its core, I think the biggest problem with the game is that the developers cannot design a good puzzle. Getting through almost every single room is a matter of noticing the one element of the environment you can interact with, whether it's a terminal you can hack, electric cables you can shoot or a door you can open remotely to fill the room with water. You use this object, and then progress to whatever it makes accessible. If the Tomb Raider or Prince of Persia games could be said to offer climbing frames, Hydrophobia offers a mile-long running track covered in rocks.
I had more fun playing out Hydrophobia's gunfights with the terrorists, which is remarkable seeing as just putting the crosshairs on a bad guy means overcoming the game's controls, camera and flypaper-like cover system. Nonetheless, the fights are entertaining because, with the exception of two rooms in the whole game, they're relatively easy. Between explosive barrels, explosive gel rounds, your Sonic rounds (think force push loaded into a pistol) and the chance to cause unexpected waves of water, you're really just spending the duration of any fight knocking ragdolls around.
I'd have liked the Malthusians to have been more than ragdolls, but weirdly, the more you find out about them and the more you hear their leader talk over the ship's intercom, the less human they become. These are pantomime villains of the lowest order - faces covered by skull-patterned scarves, the foot soldiers murder their way around the game without saying a word, and their leader is a heavily scarred woman with the charisma of a wet pamphlet.
Speaking of characters, the helpful voice in your ear for the first two acts of Hydrophobia, a character by the name of Scoot, was a Scottish man who was apparently so irritating in the original game that the developers actually recast him for Hydrophobia Prophecy. I think that's amazing, and I'd almost trade that for what we have now - a slightly acidic American voice who inspires nothing at all. (Except a bit of revulsion in the early game when he chirps, "I don't know! I've got two balls, Kate, and neither one of them is crystal.")
I didn't play the original Hydrophobia, so I'm taking all of this from the lengthy list of updates that developer Dark Energy Digital has released. But looking at that, it's easy to notice that some of the fiddliest elements of Prophecy (the floating cover system, the ability to round corners in cover, the direct water manipulation at the end) and the most tedious rooms in the entire game (the buoyancy puzzles, a horrible room that revolves around floating cover) are, in fact, entirely new to Prophecy.
That makes this less of a new, improved edition than the developers are making it out to be - but I suspect they were doomed from the start. A third-person action game boasting everything from puzzles to gunfights to exploration is a huge project to embark on, let alone one that successfully incorporates the most advanced water tech video games have ever seen.
Which I guess is the best reason to buy Hydrophobia Prophecy - not for entertainment, but as a kind of digital tourism. You're paying for a look at everything the developers achieved over Hydrophobia's exceptionally long development, and to see what this game might have been. Which, now I think about it, isn't a bad reason at all.
Hydrophobia Prophecy is out now on PC and is due this month on PlayStation 3.