New Vision is a retexturing mod for Deus Ex, which replaces the majority (80%+) of the original textures with high resolution counterparts. It's the culmination of 5 years of work, from 2007 to 2012.

It can be downloaded here on its own, with an installer that adds an updated game launcher and renderer (courtesy of Kentie), or it comes bundled with Deus Ex Revision which also updates the levels of the game (not recommended for new players). Also check out HDTP, a similar project that replaces many of the original models like characters, props, and weapons.