Activating this trainer:
If not state otherwise below, press F1 at main menu.
Listen for 'Trainer Activated'.
Press desired hotkey. All hotkeys can be changed on the trainer.

Promo Options:
NumPad5: Flashlight Brightness Charge

Trainer Options:

NumPad1: Unlimited Health
NumPad2: Unlimited Medkits
NumPad3: Unlimited Gas Mask Damage
NumPad4: Unlimited Mask Filter Time
NumPad5: Flashlight Brightness Charge
NumPad6: Unlimited Ammo / Crafting
NumPad7: No Reload
NumPad8: No Weapon Overheat
NumPad9: Creatures Don't Attack
Multiply: Unlimited Throw Items
Add: Time Of Day
Separator: Super Speed
Subtract: Always Clean Weapons
Decimal: Unlimited Pressure and Current

Notes:

Unlimited Health: Toggle on and most things cannot kill you. Some parts of the game are scripted failures.  Also if you were supposed to die, the game can crash or seem hung up, so toggle off if repeatable problems.

Unlimited Medkits: Toggle on and you have unlimited Medkits.

Unlimited Gas Mask Damage: Toggle on, and while on the mask gets no further damage.  Works best on masks that have not been broken to the point they have a hole and taped.

Unlimited Mask Filter Time: Toggle on and your filter never runs out.

Flashlight Brightness Charge: Toggle on and the light remains at maximum charge.

Unlimited Ammo / Crafting: Toggle on and your weapon ammo does not decrease when fired.  Also many other items in the game are temporarily set high and may be useful, such as for crafting items.

No Reload: Toggle on and many weapons you can fire without reloading.

No Weapon Overheat: Toggle on and many weapons do not overheat when fired.

Creatures Don't Attack: Toggle on and many non-human creatures will approach but will not attack.  Some attacks are scripted in the game.

Unlimited Throw Items: Toggle on and most items you can throw, such as knives, can be thrown unlimited.

Time Of Day: Press to set the time of day based on the value in the trainer.

Super Speed: Toggle on to speed up movement in the game to get to places quicker.

Always Clean Weapons: Toggle on and most weapons revert to 100% clean and stay that way while this is on.

Unlimited Pressure and Current: Some weapons and items use pressure or voltage to power the weapons.  Toggle this on to keep the value locked to the value you can modify in the trainer.