GEMNOD: GEM Orange + ENOD

This is really cool! It looks amazing. But here's what's interesting: Let's say someone creates a map with new objects... and someone downloads the map and wants to play it... for the objects to be in the game, does that mean the mod also needs to be installed? And if people play without the mod, what will the objects be replaced with? Will it just be empty?

Usually, in such cases, the author provides links to the required files or simply includes them in the map itself (which is also possible). For example, there's a campaign for the Green faction of Haven by RedHavenHero – it included links to the NCF engine and the required units. There's also a map called "Pirate Utopia" – it has improved creatures embedded within it.