Where's your cloak now?
— The Engineer to Spy
The Mechanical Engineer Update is an unofficial community-made update by Samuel Pires and inspired by Diamo Lima's Guard Dog Update. It was released several months prior to the official Engineer Update.
- Day 1 introduced a new building called the Mothership. It appeared as a small team-colored blimp that acts as a Dispenser. The idea of the Mothership was it was easier to move around when changing spots.
- The Mothership's downside was the gas used to fly was hydrogen, a flammable gas. If the Mothership was damaged it would explode and possibly injure both teammates and enemies.
- A snapshot was featured of a new community map called cp_generator.
- The Hellraiser was to be released on Day 2. It was a Nail Gun with a mini-container filled with radioactive gas provided by Mann Co. and nails manufactured by Saxton Hale's teeth. It was intended to give away cloaked Spy positions with a green radioactive glow.
- The infamous achievement_idle map was added as a King of the Hill map.
- The Machinist Chest was a new building that would allow Engineers to upgrade teammates' weapons with faster reloads, accessories, and other tweaks, lasting for a single life.
- The bottom of Day 4 joked about the Engineer achievements, saying "Write every single one? OK, I give up!" and ending with a message from Samuel announcing that the update was indeed fake and explaining how he was inspired by Diogo Lima and his Guard Dog Update.
- The Teleportal worked like a regular Teleporter, except the exit could be thrown to attach it to walls and ceilings, with the downside being a slower recharge time.
- 35 Engineer achievements were listed, mostly having to do with the new weapons and buildings.
- The Engineer wrote some notes next to the images of the Mothership on Day 1. He referred to it as "Engineering Project #25" and said he was getting tired of packing up and redeploying his buildings, although it wouldn't give as much metal or health compared to the stock Dispenser.
- On Day 2, written on the Hellraiser's Page, the yellow colored letters in the sentence "This masterpiece is a Radioactive nail Gun!", spell out the word "Railgun".
- Day 5 was titled "The Fake was a Lie" rather than the famous quote from Portal that has since developed into a meme. It also had "Enjoy The Cake Update" at the bottom.
- You can also see what seems to be staples next to the "F" in "THE FAKE IS A LIE" and the "C" in "ENJOY THE CAKE UPDATE"