Crysis Warhead is a stand-alone expansion pack to Crysis and although it's a good enough game mechanically, it doesn't offer anything particularly unique. Its structure reflects Crysis in many ways, with the first part mainly dealing with fighting the North Koreans. Knowing the Crysis story certainly helps with understanding why suddenly alien enemies are added to the mix. However, the focus of the campaign is not really the alien invasion.
The main character is Sergeant Michael "Psycho" Sykes, the partner of Crysis protagonist, Nomad. The story takes place in a parallel time line and covers what Psycho is doing on the opposite side of the Island after he is separated from Nomad. The first part of the game deals with fighting the North Koreans, but at a certain point, the island is suddenly flash frozen and Psycho and his team find themselves also being attacked by an alien force. Psycho is then assigned to follow a North Korean container that is believed to be carrying a nuclear warhead but is later discovered to be an alien war machine. This technology is extremely valuable as it did not self-destruct when it became disabled and the US cannot allow it to remain in Korean hands. The main mission is to follow the crate and stop the Koreans from transporting this alien warship off the island.
Story tension is attempted by Psycho's relationship with Sean O'Neill who failed an evaluation test that likely caused the death of a fellow squad member. Subsequently, his place on the Raptor team was given to Nomad. This back story unfolds through audio clips during the course of the game, although it's fairly lame and fails to generate any real emotions for the characters. Psycho apparently believes in second chances as he enlists the aid of O'Neill against his commander's wishes – a good call as O”Neill turns out to be rather handy at times.
The graphics are good and more optimized than in Crysis, although the system requirements remained high. However, as to visuals, there is a segment of the game where absolutely everything is blue. The aliens are blue, your team is blue, the landscape is blue and the Koreans are blue, making it particularly hard to distinguish your targets. I suspect this was the developers idea of conveying a frozen environment although I'm not sure it was a good one.
Mechanically, however, everything worked well. The nanosuit, which gives the wearer various superhuman abilities, returns. Controls are good and the suit wheel can be accessed and used very quickly. There's no doubt that the nanosuit is a fun gimmick to fool around with and plays a big part in your strategy. In the latter half of the game, the Koreans also have them, making things a little trickier, but overall difficulty on normal mode was not hard, although difficulty might be subjective to how experienced you are with first-person shooters. The game does have quick save and load. Once you reach the airfield, the enemies are quite sparse. In fact, too sparse until the exosuits show up. However, this is where the final boss fights take place; one with a giant Exosuit and the other with the Korean Commander, Colonel Lee Kim Sun, who has been Psycho's nemesis since the beginning.
Equipment includes binoculars and a variety of weapons, but as in Crysis, using the enemy gun type wields the most ammo. In addition, you have weapon modifications with most available right from the beginning. Vehicles are lying all over the island and easily accessible.
Crysis Warhead was received quite well, although it was criticized for being fairly short and offering nothing new. Mission segments include a main objective and one secondary. Although Psycho works alone most times, he usually has backup support and is in communication with command.
The game includes 2 versions - 32bit and 64bit.
The multiplayer, Crysis Wars, is considered a separate game, but comes packaged with Crysis Warhead at no extra charge. However, as July 2014, the servers were shut down and it's no longer officially supported. At this point, the community developed a mod to get it working. They say it will be supported until such time or if EA or Gamespy decide to relaunch. However, as I don't deal with multiplayer on the site, I can't vouch for this. General consensus is that the multiplayer is really good.
The game uses a modified version of the Drm software Securom as copy prevention, which requires authentication on installation and when online access is used. Originally, it could be installed up to five times on a limited number of machines and hardware configurations before the user had to contact EA to reset their install count. That activation limit has now been increased to 50 instead of five.
In conclusion, all I can say is ..... man, that Psycho is one ugly dude.