Impulse Tracker simply rocked. For its time, it was revolutionary: 64 channels, 99 samples, REAL stereo support on the Sound Blaster (instead of just hard-left and hard-right), disk rendering, and a whole slew of other completely awesome features that made Scream Tracker obsolete, and dealt a low blow to Fast Tracker as well. Of course the die-hard FT2 users didn't switch over anyway because Impulse Tracker had a totally different user interface... and what fool would want to learn a completely new interface after internalizing all the subtle nuances of the one they have?
Unfortunately, since IT was written for MS-DOS — and in 100% assembly language, no less — as time passed it gradually became more and more difficult to coerce it to run on new computers, and practically impossible to use on non-Windows computers. Windows-based trackers gradually started emerging (the best known being Modplug), and eventually a handful of cross-platform trackers showed up as well, but none of these had the same look and feel that IT diehards had come to know and love. Sure, they could switch to something else... but what fool would want to learn a completely new interface after internalizing all the subtle nuances of the one they have?
A handful of projects were started to make IT clones, the most prominent being Cheesetracker. However, none of these programs were intended to provide the same look-and-feel, lacked vital features like an entirely keyboard-usable interface, or were generally unstable, and most of them were abandoned by their developers. Schism Tracker's main goal is to fill this long-needed void.