Summary
Halo Zero Level Development Tool is basicly a level editor for Halo Zero which allows you to make your own modifications.
You can download the dev tool HERE
The current version of the Halo Zero Editor is 1.0.1 and has been available since 2006, and will probably not be updated anymore.
The current version of the level editor is quite unstable and you have to back the levels up quite often.
It is strongly that you check these FAQ's.
If you want to talk about modifications made by other people or made by you you should go to the forum at the forum
And at the main site you can download modifications made by other users. Plus you can find info if you want your modifications to be viewed there.
Mods
The Level Editor allows players, mainly the members of the Halo Zero Community, to mod maps.