From publisher blurb:
Rolemaster Express (RMX) is something of an experiment. It is meant to show people that Rolemaster is nowhere near as complex as it might seem at first glance.
After publishing Rolemaster Classic (RMC), ICE decided to disprove the constant rumors and misconceptions about earlier versions of Rolemaster (i.e. Rolemaster 2nd Edition, upon which RMC was based).
To do this, we created Rolemaster Express (RMX). It is the core Rolemaster engine with almost all of the options stripped out, and just a few small options implemented to ease play slightly. We packaged everything you need to play in a single, 88 page book. With RMX, you need no other books.