The game does indeed run in grayscale mode; this is intended to be a throwback to Romero's classic Night of the Living Dead. This is accomplished with GLSL, and I figured that while I was in the texel values anyway, I might as well exclude red from the list of colours to grayscale -- thus producing a duotone-style image, albeit less stark than that seen in the Sin City books.

Here's a demo -- a cow courtesy of SHilbert's unfinished TA Contest entry, PacCow (slightly modified to add red mad cow eyes!):



Run her through the engine shader:



I think the results are pretty good. I'll need a bit of aliasing to get things cleaned up properly, and do a lot of tuning to make the shader run faster. I've also added a choice to the options menu to completely disable shaders if your computer is GLSL-challenged or if your eyes are getting tired of the dark and mysterious atmosphere the screenshots thus far have evoked.

Oh... and this way, blood really turns out. Also, I've got a stats panel you can tweak your character from. More on this later.

Looking forward to more comments. [grin]