Water, that most precious of all life's commodities, is the highest prize of virtual worlds too. Land, in its immovable dependency, has always been a straightforward task for game artists. Water, by contrast, is a creature of ten thousand different forms.
So water has become an artist's calling card and a benchmark of computer performance. Turn on a tap in a videogame and you can tell a great deal about its world, the men and women who built it and the hardware that fires it. If the water's good, chances are the same care and attention runs through the rest of the experience.
Judged on this asset alone, Hydrophobia represents a high bar for the medium. As with BioShock, this is a game world straining to hold back the sea and failing. The Queen of the World, a giant ocean liner city which finds itself the stage for a terrorist attack at the game's opening, is riddled with holes: leaks that cause water to drip, stream, slosh and wash about its insides.
Shoot a barrel and the resulting explosion will cause a frothy wave to billow out around it, transparent undulations rippling off in all directions. Open a glass door to a side room in which the water is at a higher level than in corridor outside and the wave of displacement gushes out with all the credibility of a tsunami. It's impressive and, thanks to some concerted attempts to integrate it into the game's puzzles and mechanics, it's interesting too.
There's little time to stop and stare at the fluid realism, however. Kate Wilson, the improbably acrobatic security engineer whom you control, is propelled through the game with all the urgency of a high-pressure hose. Your immediate fight is against physics. The water level changes about Kate constantly, her sprints morphing to swims and back again. Wrestling Kate through the forces that buffet her is a challenge nearly matched by the one presented by the hyperactive camera, never comfortable in the tight shafts that define the game's environments and therefore requiring constant attention.
But, camera aside, this is not an un-enjoyable battle. Developer Dark Energy Digital smartly derives puzzles from changing water levels in rooms to access higher air shafts and tunnels and - at this fundamental conceptual level - should be praised for the efforts made to ensure water is more than a gimmick.
The problem, then, is everything else: the lacklustre combat, the imprecise platforming, the lack of meaningful feedback, the repetitive hunting for keys to locked doors, the over-fussy map, the intolerable cover system and the poor signposting that will leave even the most attentive player floundering for direction and purpose. These factors frustrate, pulling the game time and again under the high mark established by its water.
Access to the ship's floors is handled by way of a system of locked doors. To move to new areas you must find and kill the enemy that holds the relevant frequency key. This will enable you to read directions daubed on the wall using a handheld computer. Rendered as a series of graffiti arrows, these point the way to the relevant cipher that, when installed into your computer, will unlock the encrypted door in question. This sequence is used with such repetition that it quickly becomes tiresome, especially as you run at quarter speed when holding your MAVI computer up to read the hieroglyphic directions, needlessly slowing down what was already an uninspired hunt.