ID:1621072
 
(See the best response by Nadrew.)
My experience with "easy to use" MUD/MMO gamedev apps was... less than stellar, there was always one feature that was missing: Automatically downloading game's data (graphics, sound, etc.). I just don't want to have to make people download client whenever I add new graphics or maps.
Best response
BYOND handles resources fairly well, it'll download them for the client as needed and cache them. When new updates happen the new resources will automatically be downloaded by the client when they need to utilize said new resources, without having to manually download any updates.

That is, if they're joining a hosted server. Updates would need to be done either through the pager program, or manually when server hosts wanted to update their server's game version.