I've had fun playing rune mode, but I've noticed that sometimes a player really takes off score wise by getting a bunch of runes, and then hiding in some obscure part of the map (which can make the game less interesting since it is so unlikely to overcome). Maybe if it was easier for players to locate the runes this would happen less.
What if runes that are obscured (behind obstacles) were rendered with a wireframe? A semi-straight forward way of doing this might be to iterate through the runes after everything else has been rendered and re-render the runes as a wireframe (GL_LINE). The wireframe could be the same color as the rune normally is so that players could tell which rune is which (that is, don't set the color to grey or green as r_showtris does, but just leave the color as it is).
The wireframe runes could be rendered with depth testing and depth buffer updating turned off. And only view frustum culling should be applied (so runes culled by walls would appear). There should be no need to not render runes for that are plainly visible since the wireframes should perfectly overlay the plainly visible runes so it does not change their appearance (at least not very much).