Out of sheer curiosity and insanity, I just installed DP to check how close to Quake can I make it look.

Model interpolation is essentially required, since you can't turn off movement interpolation.

Particles are shit and blurry even at the highest quality, and apparently there's no option to make them square. They don't behave correctly, either, because way too many of them spawn, and also smoke particles seem to fade to solid black before disappearing. This is very noticeable when using the GL.

Underwater warp exists, but the actual water surface doesn't get warped. All it does is a Q3-like rotation.

No way to disable colored dynamic light, by the looks of it.

The game font is scaled at some weird size that makes it blurry with linear filtering and MSPaint-quality jaggy with nearest filtering.