Though it has some flaws and a short life-span, Hydrophobia is an impressive game.
You are Kate Wilson and when the Queen of the World city-ship is attacked by terrorists. You, armed with some horrible voice-acting, a grade eight swimming certificate and an awesome portable computer called Mavi, set out to fight back.
Of course, the main thing in this game is the water physics, so that's what I'm going to talk about first. The water acts realisticly. Electricity conducts through it, objects are sort of floating about as if you're in space and currents can be used to flow conveniently placed explosive barrels right into your enemies for some fireworks.
The interaction with water is quite realistic aswell. For example, if a nice plod of water held back from glass breaks, it will create a massive wave which will then drag you along with it. You can also drown enemies.
There is a lot of tension in this game, It's as if the ship is about to sink at any second. Also the terrorist group is basically killing off the entire ship so whether you can save a bunch of survivors in time creates a sense of urgancy.
The combat will be no stranger to you if you've played a cover thrid person shooter before. With a press of a button you can move behind cover and then shoot some terrorists and make "tomato sauce" squirt out. Though that is easier said than done as ammo is scarce in this game. You'll have to conserve it.
How to kill enemies shouldn't be a problem though. You can drown them, shoot expliosive gel at them, electrify them, blow them up with explosive barrels, or, if creativity isn't your strong point, you can easily kill them with some semi-auto rounds.
Though this game isn't Mirrors Edge, when your head is above sea level, you can do some climbing about to get higher. This involves balance beams, shimmying pipes, or simply climbing up walls. There is also a little hacking minigame for when you're feeling like Sam Fisher.
Though Hydrophobia gave me some fun, I wouldn't call it the best Arcade game ever made. If you've got some money to spend, I'm sure you can do better.