Currently we are working on making the first single player oriented release of DB. But making single player maps is a lot bigger task than making Deathmatch maps. Not only because of the scale, but also because of the number of maps needed, the number of skill settings and the testing required to make sure every problem of the map is solved before it comes into player hands. Where as deathmatch maps are best tested together with the players.
This thread has been a long time coming for DB. But it is definitely time to make a call for people interested in taking part in this game's progress. The people we are looking for are predominantly people who excel at the blocking out of a level and creating exciting scenarios for the players. If you don't have much experience with visuals, that is ok. Visual work I can do pretty easily on my own.
The editor in question is watever you prefer in terms of making Quake (3) maps. I myself (Kristus) is using a custom version of NetRadiant that I find exceptional in most ways and recommend highly. (Link: Github.com)