Fourth game from Silent Hunter series simulates the war on Pacific from perspective of American submarine commander. In campaign mode we can start on 7th December 1941, straight after the attack on Pearl Harbor. From Philippines or Hawaii we start the patrols with extended range of missions - comparing to previous games this time creators prepared not only standard partol duties, but also reconnaissance missions, delivering troops or supplies and rescuing the pilots shot down over the ocean. The game especially gains if you decide to start in the South-East Asia Fleet, where you begin from Cavite base on Philippines, but as the Japanese army advances one day you simply receive message that the base os no longer active and you have to relocate to Java. But Java also falls into hands of Japanese, so you have to retreat to Australia. Also in South-East Asia Fleet there is more variety of missions and areas to patrol, while from Hawaii you usually attack the mainland of Japan.
The graphics were improved, gameplay was improved, the crew management system introduced in Silent Hunter 3 was improved, but since the publisher decided to move forward few months the game premiere the it was so full of bugs that it was often impossible to play. Even after the patches were published a lot of problem with the game still remained f.e. Japanese planes flying over some secluded areas every 10 minutes or when the engines of the sub were damaged beyond repair the game simply got stuck with no way to repair engines, no way to abandon the boat or even call for help (same story if you run out of fuel). Thanks to mods prepared by fans the game was playable, they managed to make it quite good actually (like Trigger Maru Overhauled mod), but the disappointment was huge.
Of course there was also problem known already from Silent Hunter 3, the respawning of the Japanese warships, f.e. if you would sneak into Truk atoll you are guaranteed to find something big and helpless to attack and even if you attack the same base few weeks later again you will find great targets. The effect of that error is that you can sink a lot more ships that Japanese actually had during the war (like there were only two Yamato class battleship, but in Silent Hunter 4 you can sink any number of them you can find).
The game was also expanded with the "U-Boat Missions" pack that allowed to play the game from the point of view of German U-Boat captain operating on Indian Ocean and Pacific, but it was more novelty rather than actual expansion. On the plus side the game had quite nice system of ship damages - the enemy ships had status for different modules, which increased the realism of the game. For example if you would learn the weak points of the enemy ships you can sink them without much effort, if you would use deck gun to destroy the gun of merchant ship the enemy was defenceless. Unfortunately, since the game wasn’t properly tested, while aiming through the deck gun view you could not get any informations about the distance of enemy, even though the data was available on UZO, so you would have to switch between the two stations or just use your own judgement while shooting... One of the many small annoying errors.
Overall the game was a disaster saved by the fans and their mods, and while using the mods Silent Hunter 4 becomes the best position in the series (sadly Silent Hunter 5 was improvement in graphics, but nothint but graphics).