Duke Nukem 3D contains a number of items that will help the player to complete the levels.
All these items are used immediately when they are picked up (i.e. stepped on). If they cannot be used (i.e. if they won't affect the player), then they are not picked up, and remain on the ground.
This item immediately restores 10 health (maximum: 100).
This item immediately restores 30 health (maximum: 100).
This item immediately restores 50 health (maximum: 200).
This item immediately restores 100 armor (maximum: 100).
When picked up, these items are stored in the player's inventory. Some of the items activate automatically in specific circumstances, while others must be used manually by pressing their hotkey or selecting it in the inventory and using it.
All inventory items have a percentage associated with them, which means something different depending on the item. An inventory item can have a maximum of 100%. If a copy of that inventory item is picked up while the player's current inventory item is at less than 100%, the percentage of that inventory item is reset to 100%. If the player's current inventory item is at 100%, the player cannot pick up any copies of it, and those copies remain on the ground.
If an inventory item's percentage becomes 0, it automatically disappears from the inventory.
A piece of advanced technology that creates a holographic model of Duke (the player) in the place where it is used. The hologram does not move, and can be walked through. Its percentage represents how much longer the hologram can be displayed. The percentage drops quite slowly.
The Holoduke is used mainly in multiplayer games against other humans, since the computer's AI recognises the hologram for what it is, and pays no attention to it. This is explained as the aliens having a very keen sense of smell, and recognising the hologram as a fake as it does not have a smell.
A silver backpack that allows the player to fly through the air. Its percentage represents how much fuel it has remaining. It drains fuel quickly.
A pair of black goggles with green lenses that allow the player to see in the dark. They amplify the ambient light and shade it green. They also vividly amplify certain sprites such as enemies, weapons, items and text (often in the form of Its percentage represents its remaining battery power.
A white briefcase full of medical supplies. As its name suggests, it acts as a Medkit. Its percentage represents the number of health points it is yet able to restore. When used, it restores the player's health back to 100 (it cannot be used if the player's health is 100 or above), or as high as it can (this is the case only when the Portable Medkit is about to run out). The amount of health that it restores each use is deducted from its percentage.
The Portable Medkit's hotkey activates the Portable Medkit, and restores the player's health as much as it can (maximum: 100). The health restoration is instantaneous, as is the percentage drop of the Portable Medkit.
A pair of sturdy black boots. They protect the player from taking damage from damaging surfaces such as slime, lava and alien blood. They do not protect the player from any other environmental damage. Its percentage represents how much more exposure to damaging surfaces the Protective Boots can withstand before becoming useless. The rate at which its percentage drops depends on how damaging the floor is (more damaging floors will cause it to drop faster).
The Protective Boots do not have a hotkey. They activate automatically once the player comes into contact with a damaging floor, and deactivate as soon as the player leaves that floor.
A snorkel and an orange tank of air, perfect for underwater exploration. Its percentage represents how much air is left in its tank. The percentage drops quite slowly.
The Scuba Gear does not have a hotkey. It activates automatically once the player goes underwater, and deactivates as soon as the player surfaces.
A brown medicine bottle containing only the finest drugs. They drastically boost the player's speed for as long as they are in effect. Also, a shrunken player using them will immediately return to normal size (as well as getting the speed boost). Its percentage represents how long the speed boost will last for. When the percentage reaches 0, the player returns to their normal speed, with no adverse effects. The percentage drops quickly once used.
Access Cards come in three colours:
They are used in Access Card Panels, but only ones with the same colour. Often, using an Access Card will unlock a door to allow further progress, but sometimes they reveal switches or lower forcefields.
Only one Access Card of each colour can be carried at the same time, although in the game there is never more than one of each colour in the same level. Some user maps may use more than one, or may invent new Access Cards with different colours.