Hydro, from Canadian design student Yohei Shimomae, is a side-scrolling shoot-em-up with a methodical pace and an odd premise. Armed with a water gun, a jet-pack, and a snazzy shorts 'n t-shirt combo, you must battle a horde of flying robots that are all shaped like sea-life and have names like "Roboctopus". Somebody must have forgotten to inform your unseen robot-making nemesis that sea creatures aren't known for their ability to maneuver in the air. That is why there are so few birds shaped like tuna. And if you absolutely must build an army of airborne fish robots, don't make them vulnerable to jets of water.

But you can't tell mad scientists anything these days. This one is probably just a big fan of Darius.

Control your on-screen alter-ego with the arrow keys, and charge your water cannon by holding [space]. The longer you hold down the space bar, the better the range and duration of the blast when you release. All of your vital statistics — life bar, fuel, and weapon ammunition — have been condensed into a single tank of water. Your water supply depletes when you move, when you charge your weapon, and when you take a hit. You have but one life, but you only die when you fall off the bottom of the screen, either from running out of water completely or from an ill-timed pummeling.

Refill your water pack by picking up floating blue orbs. Destroy enough mechanical seafood, and a random bonus letter will appear. Grab it to power up your range, damage, charge time, or flight speed. And avoid getting hit, because you'll lose one of your bonuses if you do.

Analysis: Hydro has an unusual feel for a shooter. Because of your weapon's extremely short range and the enemy's almost total lack of projectiles, you have to confront your targets face to face. So you are always charging headlong into danger with limited resources. Although the water refills are spaced out regularly over the long run, their frequency has peaks and valleys. You can't afford to waste water moving around unnecessarily.

This makes Hydro into something of a thinking shooter, in which you must plan your moves and manage your resources. Well, your single resource. Don't get me wrong. This game won't put undue pressure on either your brain or your reflexes. It's just a simple, well-told story of a flying man and his deadly water pistol.

The presentation is appealing, with slick cartoony artwork, smooth animation, and a hypnotic throb of a soundtrack (which, again, sounds a lot like something from Darius). The end-level bosses are menacingly lovely, composed of rotating limbs and armor that often can be knocked off in pieces. The collision detection gets a little weird around some of the rotating creatures, but that's one of the few criticisms I have about the gameplay.

It's too bad that there's only three levels, but when you win, the game cycles you back through them with tougher enemies, so you can try for a high score and keep racking up bonuses. The random power-ups have a subtle effect on your strategy, enough to give the game a little replay value.

And like most side-scrolling action games, that's where it all falls down, of course. Once you beat the game, you'll be pretty much done with it. But it's a tasty bowl of bouillabaisse while it lasts.

Play Hydro