As we enter one of the most crammed release windows the video game industry has ever seen it's easy to get carried away and focus on the main headline grabbers. We know Gears 2, Resistance 2, Fallout 3, LittleBigPlanet, Far Cry 2, Mirror's Edge and Prince of Persia are going to be massive games, but what about EA and Crytek's Crysis Warhead, the stand alone expansion to last year's utterly brilliant and stunning PC only FPS? For PC gamers this is a massive release and we reckon it's the finest six hours of gameplay you'll have played this year.

Warhead follows Crysis' Psycho, the brutish cockney who was more or less a side character to Nomad (the lead in the first game), in a storyline that runs alongside that of the original. As in last year's game, expect to encounter dense jungle environments, barren ice fields, Korean soldiers and plenty of flying aliens. There's no denying that this is more of the same, except here it's a more tightly woven experience with a little less freedom to explore. The levels this time around are more linear but you won't get a moment of peace long enough to notice.

In Crytek's first entry in the series it took quite a while for aliens to appear, with the opening levels focussing entirely on combat against a mobile and intelligent Korean army. In Warhead the Koreans are once again highly competent but aliens come onto the scene a lot quicker. We felt that this point in the original game saw the quality take a slight dive, but here you're on a rollercoaster from start to finish in what must be one of the most relentless action games ever made. Many fans of the first game called for a sequel with less alien encounters, but Warhead may make them change their minds - we lost count of the number of heart pounding fire-fights with the glowing alien foes, and the Koreans often turned up for good measure.

As in Crysis a key component of Warhead's success is the Nano suit Psycho wears. This advanced military outfit allows you to tap into enhanced strength, increased speed, improved armour, and a cloak for a limited amount of time. The ability to quickly switch between these during combat makes for some incredible unscripted fights, with explosions, flying bodies, vehicles and a seemingly unstoppable killing machine. For many the suit's time restrictions on abilities will feel annoying, hampering what could have been the ultimate super hero game, but the biggest rewards come when you learn how to best use these abilities in different situations.

It seems as though Warhead is over in a blink of an eye and the reality isn't much longer. If you've clocked up extensive hours with the original game then you could run through Warhead in around five hours, with a few more possible if you take your time and veer off the beaten track now and again. With the amount of jaw dropping sequences crammed in by the end it'll feel like you've watched Cliffhanger, Aliens and Predator back-to-back having had your eyes injected repeatedly with Red Bull. Warhead is the kind of game that's hard to keep playing, not because it's bad but because it's such an assault on the senses.

Visually only the original game can compete

With a top-end PC (although Warhead has supposedly benefited from an improved game engine you'll still need a fairly beefy system) and a quality sound set-up it's impossible not to get completely engrossed. We've seen some impressive games since Crysis landed late last year, yet Warhead is still unmatched in terms of presentation. You'll see things that make you sit back in your chair in awe, pausing to gather people so they can see it too. The audio work fits perfectly, giving the on-screen action even more oomph and intensity. It's easy to assume a PC only release can't be up there with the multi-million dollar console epics that gamers get so worked up about, but there are things in Crysis Warhead that consoles only dream about.

Sadly it all does come to an end, but with the variety in the way you can approach each encounter there's plenty of replay value. Crytek has also shipped Crysis Wars with Warhead, an improved multiplayer offering for up to 32 players. Warhead ships with 21 maps, team mode Power Struggle, Instant Action (deathmatch) and Team Instant Action (team deathmatch). We didn't really get into the first game's multiplayer, giving up soon after our review hit the site, but Warhead seems easier to get into and more fun. We still don't know if it'll have enough appeal to form a massive fan base, but it's well worth a look once you've blasted through the campaign.

When EA and Crytek announced that Warhead wasn't a sequel but an expansion there were a few understandable groans of disappointment. After the success of Crysis people wanted a full-on sequel that would move the series forward in the way Crysis built on the foundations laid in the Crytek developed PC Far Cry. It's fair to say that we didn't expect an expansion to be this good. Considering you can shop around and pick Warhead up for £15 you'd have to be mad (or a psycho) to overlook it. If you've got a modern PC and a longing for some macho man action packed gaming, Warhead is an essential purchase.