A better rendering-engine is a no-brainer—the original shadows tend to become olive-banded messes—but my experience with texture-pack mods isn't as good. IIRC

A better rendering-engine is a no-brainer—the original shadows tend to become olive-banded messes—but my experience with texture-pack mods isn't as good. IIRC they tended to make the overall experience worse, with jarring inconsistencies of high-poly/high-res objects versus unmodified portions of the environment. Plus nowadays "low res" is sometimes it's own art-style. :p