So I was checking around the interwebz, looking for a way to activate the cheats in single player mode. Well, they had youtube videos demonstrating the cheats... in other languages... but not how to activate them. Well being an avid configuration changer, I did some snooping and found the correct files to change.
Here is the file directory to turn cheat mode on:
C:\Program Files (x86)\Steam\steamapps\common\the-haunted-hells-reach\UDKGame\Config
Once there, look for the settings that say DefaultGame
Press CTRL+F when in the file, and type in Cheat, then press enter. Change the false right after the word cheats to true, and don't worry about the debug thing afterword.
You can now activate cheats such as size changer (ChangeSize 1 + Default), God mode (God), and other cheats.
A helpful way to get guns fast (THIS WORKS ON MULTIPLAYER). In the same directory listed above, go to the configuration file that says DefaultWeapon. Scroll down through the file and change all of the experience notes to a desired multiplicative factor. Let's say, for instance, the pistol multiplyer says 1. If you change it to 5, for every kill that you get with that pistol, you get 5 times the normal experience.
Hope this helps a bit.