While I was browsing the game's files, I came across a debug mode and began writing up on it for The Cutting Room Floor. One unusual thing about ElecHead's debug mode is that it is fully accessible without modding tools or cheat engines!

Simply hold Shift Left, Shift Right and D during gameplay (or Start, Select and B if you're using a Nintendo Switch controller) and text reading "DEBUG MODE ON" should appear. From here, you can press either of the Shift or Crtl keys to do different things.

*Right Shift OR RB - Toggle free movement. You can't clip through walls, however.
*Left Shift + B OR LB + A - Toggle head throwing ability.
*Left Shift + Y OR LB + A - Toggle rocket head ability.
*Left Shift + G - Show grid overlay. This was used during testing to check if all the objects were aligned properly.
*Left Shift + F - Toggle Game Maker Studio FPS on the top left.
*Left Shift + C - Toggle CRT screen effect.
*Left Shift + P - Scroll through all 16 available palettes, regardless if they've been unlocked or not.
*Crtl + V - Reload soundVolume.txt and reset volume settings.
*Crtl + G - Record GIF. Press again to stop recording. The output file is saved as %localappdata%/ElecHead/elechead_XXXXX.XX.gif. X represents the date and time outputted as a string.
*Crtl + S - Take a screenshot. The output file is saved as %localappdata%/ElecHead/screenshot_DD-MM-YYYY_HH_MM_SS.png.
*Crtl + L - Toggle camera. Disabling it will disable transitions when moving to another screen.

I also found a leftover scrapped function called "keyDebugWarp", likely leftover from an earlier phase of development when you couldn't warp to previous portals. It has some code, but no key inputs set by default.

And of course, use this mode responsibly, and not to unlock achievements or run through the game on your first playthrough.
Enjoy!