versuch mal
d3d_mipmapping = 0; // no mipmapping
oder
var mip_shaded = 2; // let shaded block textures appear sharper in the distance.

Some small recent games of mine:
Griefer 4k http://damocles11.byethost9.com/griefer4k.html
Kobold 4k http://damocles11.byethost9.com/kobold.html
Cave 4k http://damocles11.byethost9.com/cave4k.html