To unlock the simplified 3d person view, do the following. Open the "preyconfig.cfg" file which you can get from the game folder in your text editor. Note that it’s recommended to create its backup before proceeding. When it’s done, add the following line to that file. Save the file and return to the game. Press P to enable the effect.
bind "p""toggle pm_thirdperson"
Now I’ll teach you how to simplify access to the console window. If you use this cheat, you will be able to enable it by pressing “~”. Just start the game with the parameter "+set com_allowConsole 1" typed in the command line.
Do the following achievements to enable the desired effect:
Casino Mode: complete the game and choose "New Game" to see "Casino mode" above Normal mode. Casino mode allows you to play the casino games in Jen's Bar.
Cherokee mode: complete the game on the Normal difficulty setting.
Concept art galleries: complete the game on the Normal difficulty setting to unlock the first gallery and complete the game on the Cherokee difficulty setting to unlock the second gallery.