To get his feet wet after not paying attention to ZDoom for a while, TehRealSalt decided to take a stab at remaking the Mirror Mode he did for SRB2Kart, but in ZScript form instead of C. Really simple trick, just flips the screen, then flips strafing and looking. Requires OpenGL for the shader, but otherwise should be compatible with just about everything. Far from perfect, but a lot of the issues would only be solvable as an EXE modification. More information can be found at the release thread. Known issues are:

• Might be a little messy with MP prediction (confirm?). May update this in the future to try and use PlayerThink, but I want to make sure it maintains its current level of compatibility.
• Sounds are flipped. Not much I can do about this one.
• Automap is wrong too, which I probably also can't do anything about.
• Occasional, really subtle mouse jitter with rendering interpolation. Yep, also can't do anything about this.