Free Mod Manager for AC!

[Mael]

But,

AssaultCube allows 3rd party developers to "MOD" the game by using the existing AssaultCube engine/data for their own modifications, so long as they don't break any of the license agreements for the particular media they're modifying.

However, many don't realise that you can release your MOD without needing to overwrite existing data (a.k.a: content replacement). The advantage of this is that it allows you to add MODS cleanly without placing the files inside the main AssaultCube directory. This means, that if you don't want to play AssaultCube using the MOD, or want to play AssaultCube using a different MOD, you can without having to install several copies of AssaultCube.

http://assault.cubers.net/docs/mods.html