Guerrilla Games' Killzone series has gotten better with each released game. It started on the PlayStation 2 eight years ago, but I can honestly say that it really got its footing on the PlayStation 3 with the much improved Killzone 2, then really hit its stride with the graphically superb – and awesome-playing – Killzone 3. And while the series is sure to continue on its merry little way with the forthcoming Killzone: Mercenary for PS Vita (which is slated for a 2013 release), Guerrilla felt like it'd be an ideal time to revisit the game that started it all.

Last month, the company announced Killzone HD, a 720p-powered retouching of the PS2 series starter, which is slated to arrive for PlayStation Network this week for $14.99. You can buy it separately and enjoy it to your heart's content, or, if you've never played the series, you can also pick it up as a package deal in this Tuesday's retail release of the Killzone Trilogy for $39.99, which also includes 2 and 3, as well as its coordinating downloadable content.

We got our hands on a finished build of the HD remake, just to see how it would fare…

If you're not familiar with the story, it takes place in the 24th century, on the planet of Vekta. An invading force of soldiers known as the Helghast have taken up occupation of the planet, driving people into madness with their military tactics. With the help of hot-headed sergeant Rico, Shadow Marshal Luger, and former Helghast spy Hakha, the leader of the rebellious ISA, Captain Jan Templar, steps forward to make things right – by any means necessary.

When Killzone was first released for the PlayStation 2 years ago, Sony dubbed it a "Halo killer," but reception wasn't received like that from the fans. Regardless, several did applaud Guerrilla for introducing an intriguing storyline, along with plenty of intense first-person shooting action. We're happy to report that this familiar level of action is not only present and accounted for in Killzone HD, but also improved.

The gameplay seems to have been fine tuned a bit, so that the guns are actually more accurate as you aim and shoot them, as well as looking down the iron sights when you're shooting at a forthcoming soldier, or trying to devastate a tank with a rocket launcher. Sniping has majorly improved over the first game, as it's easier to look and zoom through your scope and pinpoint your targets, mostly Helghast soldiers who are taking pot-shots at you from above. It's great to see these improvements, and players who grew up with the series will likely give this one a second chance as a result.

In addition, Guerrilla Games reworked the graphics from the first game, and while it's still a little jagged in bits and pieces, it's definitely a push up from what we saw back on the PS2. Helghan soldiers still look like a huge menace when they come lumbering into the battlefield, and the torn-apart city that you'll run through still has plenty of haunting remnants, especially after you head into upstairs sections and see how badly everything's gutted.

The action moves at a frantic pace, and though sometimes it's a bit easy losing sight of an enemy (when they shoot at you, you can see which direction the bullets hit you from, thanks to helpful blood-red on-screen indicators), it's a rush. What's more, the 720p support makes this game look better than ever, even though it's still miles away from the magnificent Killzone 3. But, hey, sometimes a series progresses like that.

Along with the main story mode, which will take you a few hours to get through, there's also a Battlefields mode, where you can battle with your friends in off-line co-op action against AI enemies. Though it's disappointing the game doesn't take full advantage of the PlayStation Network, this mode definitely helps you get your first-person shooting chops up. And besides, if purchase the Killzone Trilogy package, you'll have plenty to do between Killzone 2 and Killzone 3 anyway, especially with the downloadable maps.

As we stated, Killzone HD is on the disc in the Trilogy package, but, unfortunately, it still has a mandatory install of about 3 GB, a huge amount for an "older" game. So, if you already have the previous Killzones, there's no shame in purchasing it for download, as it'll take up the same amount of space.

Even though it couldn't come close to Halo at the time, and seems a little "ancient" compared to other first-person shooters these days, Killzone HD still looks like a quality effort from Guerrilla. Be sure to check it out this Tuesday when it debuts both on the PlayStation Network and in the Trilogy collection.