The suit's integral facemask has its own HUD, displaying typical data including a tactical map, health, current energy levels, and weapons information. The view is electronic in nature, shown in-game through things such as a booting readout and visual distortion during abnormal operation. A particularly useful utility is the binocular function, which allows the player to zoom in and electronically tag enemies and vehicles from afar, thereby tracking their movement on the tactical display.
The player can engage enemies in a variety of ways; using stealth or aggression, bullets or non-lethal tranquilizers, ranged rifles or short-range weaponry, and so on. Enemy soldiers employ tactical maneuvers and work as squads. All soldiers will respond to noise caused by the player, including using signal flares to call for reinforcements. If the player has not been detected in the area, enemies will exhibit relaxed behaviour, but if aware of the player they will draw weapons and become combative.
Weapons
The game features assault rifles, sub-machine guns, pistols, missile launchers, shotguns, miniguns, sniper rifles, gauss rifles (coilguns), the MOAC (a machine gun style alien weapon which fires high-velocity ice shards), and the TAC gun (a hand-held nuclear grenade launcher). Most weapons can be modified with attachments; these attachments may be given to the player by default, acquired from picked-up weapons, or purchased in multiplayer. Attachment options are given a fair amount of leeway even if the end result may seem strange. For instance, a 4x/10x sniper scope can be attached to the buckshot-firing shotgun, though there might no practical use for such a particular combination. Additionally, most weapons have multiple firing modes (single/automatic fire) and different ammo types; for example, the KPA's FY-71 can fire both conventional bullets as well as incendiary bullets, which increase damage. Crysis also incorporates some features that have appeared in other recent shooters such as accounting for already-chambered rounds when a reload occurs.
Vehicles
A large selection of vehicles are present, most of which are usable by the player. Available ground vehicles range from pickup trucks to tanks, while naval vessels range from motorboats to light military hovercraft. A larger patrol boat is available in custom-made multiplayer maps using the sandbox editor. All vehicles, including Humvees, pickup trucks, even tanks, have a turbo mode that can be activated via the Shift key (by default). The aircraft selection is limited to the North Korean attack helicopter and a fictional American VTOL (each of which can transport six passengers and two crew). Crytek also included an amphibious armored personnel carrier, its wheeled version that can travel on water and land, although this vehicle was only available for those who pre-ordered the game.
Damage modeling, although limited in vehicles, is most noticeable in the ability to burst tires, although wheeled vehicles can still move even if all the tires are gone, slowly rolling along on the rims. Tracked vehicles such as tanks or APCs can lose their tracks as a result of damage, but may continue moving even though there is no way for the drive sprockets to propel the vehicle. Exposed gas cans on Humvees can be shot in order to detonate their contents, which usually results in the explosion of the vehicle. While burning, destroyed vehicles will cause proximity heat damage to objects and characters. Unavailable vehicles shown in-game include jet aircraft, excavator, forklift and for reasons of scale, destroyers. None of the alien machines can be commandeered by players. The wheeled carts which would presumably be used to move aircraft or heavy vehicles, can also be moved by the player, but movement is very slow and useful for little more than entertainment and novelty.
Multiplayer
Up to 32 players are supported in each multiplayer match in Crysis multiplayer, which used the GameSpy Network and required the user to have an existing user ID or otherwise create a new one. There are two different modes, each with six available maps: Instant Action, a deathmatch type mode; and Power Struggle, which is played by two opposing teams, each trying to destroy the other's headquarters.
Power Struggle features the American soldiers fighting the North Koreans; both sides, however, have nanosuits. All players begin armed with only a pistol and a nanosuit. Weapons and vehicles can be found throughout the map, but generally must be bought by using "Prestige Points," which are earned by killing enemies or capturing buildings.
The aim of Power Struggle is to destroy the enemy headquarters, a task which is achieved using nuclear weapons in the form of a TAC Tank, a TAC launcher, or by using a Singularity Tank, which generates a temporary black hole in the target area. To gain access to nuclear or singularity weapons, the player must first capture the "prototype facility" which is used to make them, and then use the alien crash sites which feed the facility with energy necessary to build up enough energy to build weapons of mass destruction.
