Newcube is a mod of Cube I made ages ago. It's not very playable, but does have a cool single-player campaign and a few new maps. Here is a list of just some of the features:
* New trigger effects.
* Re-integrated LOD.
* All new music.
* Fixed loads of bugs.
* Improved savemap (doesn't mangle precise texturing).
* New sky boxes from Skiingpenguins (they're well cool).
* Improved the particle effects.
* All new textures.
* Improved the weapon selection system.
* Skill level is now saved when you quit the game.
* Red menus.
* All new enemies and guns.
* Independent monster sight sounds (ooh, I'm proud of that).
* Improved game modes with bug fixes.
* Fall damage.
* Fire particle effect.
* An improved editing interface.
* Guaranteed nought percent Braille.
Download it here.
And make sure to look out for a supreme Newcube-based game, coming in a very long time.
Have fun (or at least try to)!