Redpill

Redpill (also abbreviated as RP) is a term adopted by Microsoft to denote feature hiding efforts. It was first spotted in build 6608, along with its counterpart Bluepill. Despite this fact, most associate Redpill with Windows 8 only. This can be attributed to Windows 7 using the term rather sparingly.

Windows 7
Enabling hidden features is done entirely through the registry. Checks that determine whether a new feature gets enabled are usually present within the library or executable that implements said new feature, for example explorer, shell32, or stobject. The refreshed versions of the inbox apps Calculator, Paint, Sticky Notes, and Wordpad are an exception to this rule, as the checks that guard them make use of its counterpart — Bluepill, which lives inside the Application Compatibility Engine. The resulting operation is still a registry check, albeit indirect. Redpill is included from build 6608 to build 6956.

Features hidden by Redpill in Windows 7 include the Superbar, Desktop slideshow, Start Menu pinning, Jump lists, a variety of Internet Explorer 8 enhancements, as well as the new Aero gestures such as Peek and Shake.

Windows 8
Feature control is now split into two parts.

Licensing
Values that control hidden features are much harder to modify reliably, thanks to Redpill being intertwined with licensing. Product policies, a set of values usually used to determine what a particular edition can or cannot do, are now also used to control shell features.

The correct method of delivering these policies into an existing install (clean installs do not ship with them) was activating against the internal win8act server with the parameter. Due to the majority of licensing data being signed, as well as being handled largely at kernel level, editing it manually implies the need to sacrifice parts of licensing functionality.

shsxs.dll
Besides product policy sourced values, a sizable chunk of behavior hidden by Redpill also depends on an external library called shsxs.dll. This library is home to a large set of image and DirectUI markup assets, as well as a handful of functions used to initialize various parts of Metro such as Charms, Start screen search, and the PC settings application.

If the above requirements are fully satisfied, features will get enabled. Noteworthy features hidden behind Redpill include the Start Screen, redesigned logon UI, new OOBE, Ribbon in Explorer, new Aero resources, and the pattern login (which later became the picture password login).

It should be noted that while a majority of Windows 8's protection is licensing based, old fashioned registry checks remained the method of choice in some areas.

Unlockers
There are several applications developed to enable the hidden features.

RedPill Enabler
RedPill Enabler (also known as the MDL Redpill Enabler after the forum where it was first published on) was the one of the first public applications meant to enable features restricted by Redpill. It was developed by Vizion, a member of the My Digital Life forum, and was initially released on 2011-06-17.

It works by replacing slc.dll, the Software Licensing Client DLL, with a modified one that returns desired Redpill values when prompted. Due to certain queries being moved from SLC into the kernel in Windows 8, this approach failed to work as a patch for the entire system. It also includes a set of icons for the ribbon explorer to replace the placeholder ones that some builds used and a copy of the new Task Manager from build 7971. The tool also lets users pre-unlock Windows images, simply by pointing it to a build's install.wim file.

RedPill Enabler has faced a variety of criticism over the time. Complaints include the code being poorly written, obfuscated, slow, as well as using replacement resources of dubious origin.

Metro Unlocker
Metro Unlocker (also known as MetroUnlocker or simply MU) is a tool developed by MetroFetro, a YouTuber and developer. It was the first public application that allowed for all restricted features to be enabled, including the Start screen, and remained the only application to do this from its initial release in 2016 until the release of Redlock in 2020.

The first version, released on 2016-01-03, only supported build 8056, and worked by disabling the Software Protection Service, the Windows service responsible for Windows licensing, and importing in the licensing policies from build 8102, which included the policies needed for Redpill. It also dropped a modified version of 8102's shsxs.dll. Version 2, released on 2019-03-15, added the ability to "enable" the Immersive Browser by importing in the files and registry entries for it from build 8102. Version 3, released on 2019-05-10, used the Immersive Browser files for 8056, along with adding in support for builds 8032 and 7989. The latest version, version 4 released on 2019-08-05, dynamically writes in the RP policies instead of overwriting all policies with the ones from 8102, introduced a slc.dll hack to enable the Immersive Control Panel's personalization settings for build 8056, and introduced support for builds 7927 to 8056.

This tool faces criticism due to the continued choices of crude approaches, namely the reuse of resources contained in Windows Developer Preview and build 8056 instead of working with files already provided by the build it's being run on.

Redlock
Redlock is a tool developed by lucasm and gus33000, two BetaWiki members and software developers. The initial version was released on 2020-01-29. The tool is designed to replicate Microsoft's original Redpill implementation as closely as possible. It is being actively developed.

While the practice of disabling the Software Protection Service is still present, there is a variety of improvements. One of them is the creation of a dynamically tailored shsxs.dll, making the tool's compatibility scope much wider. Product policies, system certificates, manifests and registry keys are applied dynamically as well. DISM is used to install the Immersive Browser. To demonstrate the accent capabilities of various early builds, it includes a copy of the Windows Developer Preview accent modified in order to be colorizable. Redlock is notable for being the first Redpill tool to include support for build 7850.

Compared to the previous third party tools, Redlock has been favored for its compact size, speed, and cleaner method of enabling the features.