This mod removes the restrictions on what can be built in the singleplayer campaigns;
both you and the AI can build any unit or building. Ever wanted to have a nuclear exchange on the first map?
Now you can.
Note: this mod alters the singleplayer campaign, and thus may not work properly or show up in the mod list if you have other mods installed that alter the campaign.
Since the default mods.scd contains such a mod, you may need to remove or rename it for this mod to show up.
People have reported it as working even when it doesn't show up in the list, but this is not guaranteed.