Added an option for nearest neighbor (change filter mode in the options). It makes the image much sharper, but I don't notice much difference in the stereogram effect. Let me know if it helps; I might make it the default if people prefer it.
Actually playable now, Good work!
Although as others have mentioned the depth is the most limiting factor, I keep being killed by enemies that are out of vision range. And I never really played much DOOM so it took me quite a while to figure out that a wall was actually a door, the monochrome vision really hurts in that regard.
But it's a neat experience.