The original Twilight 2000 box set is getting hard to find these days. The recent Kickstarter for T2000 4e has increased demand for the classic version.
Well, a fantastic substitute is available: The official Twilight 2000 1st Edition Reprint from FFE. This paperback contains the 1e Core Rules, plus the Poland Campaign… all in One Book.
EDIT Dec 6, 2020
I’ve been told that they are out-of-print, and FFE’s supply of them is gone. They will not be printed again.
Twilight: 2000 (1st edition) – Reprint book
2003 … Frank Chadwick, et al … FFE 2001 … ISBN 1558782273
A paperback anthology of the original Twilight: 2000 1e RPG rules, plus the Poland Campaign modules: Free City of Krakow, Pirates of the Vistula, Ruins of Warsaw, and Black Madonna.
See also: My deep-dive into the original: Twilight: 2000 (1st Edition Box Set) – Photo Gallery
A Look Inside
All 4 Poland Campaign adventures are included. Five, if you include the introductory scenario Escape From Kalisz.
Bonus content in the back: A Twilight 2000 Combat Example, and The Compleat NPC. From Challenge Magazine articles.