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.

In Windows 7, Bluepill features were to be enabled through the registry. However, Windows 8 utilizes a licensing policy and an external library called, both of which are responsible for the hidden features that Redpill can provide. Over time, several applications were developed in effort to enable these hidden features with varying degrees of success.

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 7022.

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.

Inclusion in Windows 8
Nearly all builds from Milestone 1 to shortly after the Developer Preview (currently 7779 to 8118 have Redpill implemented. Exceptions and special cases are:
 * Builds in the  and   branches. These were used for certain builds released Microsoft through the Ecosystem Engineering Access Program (EEAP), which do not have any form of Redpill implemented as all of the Metro components were removed at compile time, such as build 8064 and the EEAP release of build 8102.
 * Windows 8 build 8102 in general (except for the EEAP one), which has Redpill already activated by default. It can be disabled in the Registry.

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

RedPill Enabler

 * Main article: 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 17 June 2011.

Metro Unlocker

 * Main article: 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.

Redlock

 * Main article: Redlock

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