Activity Centers

Activity Centers was a Microsoft Windows feature originally intended for Windows ME, then Windows Neptune, then Windows XP, before being scrapped early on in XP's development.

Activity Centers would have been single-window applications, written in a combination of HTML and the Win32 API, that facilitate easy ways to complete common tasks. In Neptune build 5111, Mars.exe serves as the framework (hence, the name "Mars Framework") for running such web pages as framed applications. Mars uses the XML file in the folder of an Activity Center as the page's main layout. The  also appears to be the number one dependency of this app, which Ken found when fiddling around with various msjava installations to get the Game Center in that build working.

By default, Activity Centers would have opened to a "home page", which would contain links to the top priority tasks exposed by the application. Secondary Task pages would have provided the user with obvious ways to complete single tasks.

The user interface would have been divided horizontally into a "navbar" and a larger content area. The navbar would have provided a simplified navigational scheme similar to that in a Web browser, so that "back" and "forward" buttons are provided along with other common buttons.

Windows ME was originally envisioned to include several Activity Centers. The Start page, Photo Center, Music Center, Help Center, and System Restore are available but hidden by default in Windows ME build 2358 However, according to Paul Thurrott, by the release of Beta 1 in the fall of 1999, it was clear that the underlying Activity Center technology was not going to be far enough along to provide the needed HTML hooks into the more traditional Win32 interface. Therefore, only the Help Center (renamed Help and Support Center) and System Restore shipped in Windows ME RTM. AutoUpdate, intended to be an Activity Center, became a traditional application. Windows Media Player was expanded and redesigned to perform the features intended for the Music Center.

Neptune build 5111 came with the Start page, Photo Center, Music Center, Game Center, Help and Support Center, and Microsoft AutoUpdate. The first four could be installed by following these steps. According to Twitter user Albacore (@thebookisclosed), these Neptune Activity Centers could also run on Windows ME build 2380, and made available two files that should be copied into the  folder of the build's ISO before installation so that the Activity Centers work by default.

Windows Whistler build 2250 contained a Startpage (no spaces) at. Build 2257 contained the same Activity Centers in Neptune build 5111. Build 2410 contained a redesigned Startpage. According to Twitter user Albacore (@thebookisclosed), the Start button in build 2410 is mapped to the Startpage.

Windows XP source code
BetaArchive user TinaMeineKatze pointed out that what look like Activity Centers concept art screenshots are available in the Windows XP source code that leaked in 2020.

BetaArchive forum

 * Whistler 2250 Startpage
 * Im Trying to Fix Neptune's Activity Center :D
 * Neptune's Activity Center...
 * Neptune's activity centers image?
 * Activity Center in Longhorn
 * Whistler Build 2250 and the "Activity Center"
 * Neptune Activity Center Vid *Trimmed down*
 * Windows ME Activity Centers
 * Design similarities between Metro and Whistler\Neptune UI?
 * Windows Neptune concepts...
 * Windows Neptune Build 5111
 * "MARS.EXE" Question Neputne 5111
 * Neptune Activity Center Problem
 * Neptune Activity Center (by KenOath)
 * Windows Neptune Activity Centers Working in WindowsME & 2419
 * [RELEAK] Windows Me build 2358
 * Activity Centers retrospective: From ME to Neptune to XP