NOTE: DO NOT ENABLE SV_CHEATS OR ELSE YOU WON'T GET THE ACHIEVEMENTS

So, in the game the purple hat, which is a physics prop, is named quaff. This name is what the Lambda Core teleporter searches for when you go through; as long as the prop is named quaff, it counts as a "hat."

Load up the last Lambda Core map through the in-game console. To enable the console, go into Options > Keyboard > Advanced and check the option Enable Developer Console. Type in the text in bold and press enter: map bm_c3a2h

Your game should load up the last Lambda Core map. When it loads you into the game, you should already have a competent selection of weapons. Proceed as usual to when the scientist and Hunter are talking to you. Find a physics prop (a prop you can pick up with the "use" key and move around).

Place your crosshair directly on the prop and open up the console again, typing in and pressing enter this: ent_setname quaff


What you have done is set the name of the prop to quaff, which will make the Lambda teleporter believe it is the hat. So carry the prop with you to the teleporter room, and go through the sequence as usual. To make the sequence easier, drop the prop in an easily accessible place and aim your cursor at an empty space on the floor.

Open up console and enter the following: npc_create_equipment weapon_357

Then enter this: npc_create npc_human_security

This will spawn a security guard with a revolver who will help you. You can do this multiple times on empty spaces on the floor, so make sure to build up an army.


Now wait until the teleporter is ready, then take the prop you named "quaff" and jump into the portal.

Congrats! You now have the achievement!