This is one of the coolest tools to come along in a long time. It does just what the name would suggest... it allows you to view maps. It works a lot like Forge's visual mode... except it has a few extra features. Up and down motion is supported (shades of Pfhorte's viewer), and maps can be viewed fully-textured down to wireframe, with almost anything in between. It requires OpenGL, a 3D-rendering interface which is becoming quite common. OpenGL on a 3dfx card requires full-screen mode, which the Viewer doesn't support, but if you have an ATI Rage Pro or Rage 128 (or, according to Apple, the Rage II), get Apple's version. The viewer handles the full range of Marathons... M1, M2, and Infinity. (A first for M1 maps!) It's really slow on my Powerbook G3 (Rage Pro, but only 2 megs, I think..), but being able to fly through Pfhor Your Eyes Only... wow. Prefs are hardcoded (you can change them with Resedit, but...), but speed is variable, you can turn off the (pretty cool) "walk through walls", and it now does portal rendering, significantly speeding things up, in my experience. Additionally, stretched textures (a la Missed Island) now display correctly.) A must-have! v1.3 adds a text status display, the ability to set starting postion, and improved portal clipping. v1.4 adds the use of z-buffering, a framerate display, and some sorting options... big steps, in actuality. 1.4.1 fixes a small bug in the GL rendering code... pretty minor, but Loren says a bug's a bug.