To access the cheats, download the game (offline) and open the readme file. If you're too lazy to do that, here is the entire text of the readme:

_________________________________________
Story:

Your team's journey to explore new planets has had a horrific end-
you've crash-landed on an apparently deserted jungle planet known to your group as Harxon,
and you wake up to find yourself bruised, bloody, but somehow alive. The rest of
your team has perished, along with the ship you came in. You find yourself
shaking. Is this what it is like to be alone? Armed with only a weak gun, a lantern,
and your own wits, you venture to explore a deathly-looking building covered in vines and dead hopes.
Can you find a way out of this living hell? Or will you perish?
_________
Controls:

W - Up
A - Strafe left
S - Back
D - Strafe right

Mouse - Look
Left mouse - Fire

C - Bring up cheat console
P - Enter a password
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Items:

Health pack: Not very common, but useful. Restores 25% of your health.
______
Areas:

Main base
Dungeons
Restricted sectors
Threshold of Despair
_________________
Cheats/Passwords:

Passwords:

Level 2 (Dungeons): room_dungeons
Level 3 (Restricted sectors): room_restricted
Level 4 (Threshold): room_threshold
Level (5?): ??

Cheats (Press 'C' to show console):

Restore health: helpme
Add 25 to score: addscore
Next level: nextlevel
Last level: lastlevel
Kill monsters on sight: worldpeace
Commit suicide: suicide