Rebel XP was the first version no longer distributed on cdrom but via the Internet only and it was a free download for those who bought the previous version. The Rebel author was in the process finishing his career. Rebel XP was advertised as 33 ELO stronger than its predecessor Rebel Century 4.0 and as a feature the thinking process of the engine was further visualized.
A funny cartoon appeared on the Internet which gave us a good laugh. In reality the Windows version was already in development and was released the next year as REBEL 12 for Windows in cooperation with Lokasoft, see its contents.
This is the long awaited windows version of Ed Schröders Rebel program. Rebel 12 comes with the ChessPartner interface. The chess engine is programmed using the so called Winboard Protocol, this makes it possible to use the engine under other interfaces although it works best under the ChessPartner interface.
Unfortunately the SSDF rating list guys never tested this last DOS version that was intended to be a playing strength improvement against other computers.
This leaves Rebel Century 4.0 of 2001 as the last rated version after Ed announced to retire from active competition.
It was a good time to stop, after 22 years REBEL still belonged to the top-5, not counting double authors.