Populous Mod Manager is a program made by Populous fans (Devilhu and Deszike) that allows you to switch between singleplayers, if they are on the modmanager, or pick and play stand-alone levels. It's very easy to use, and if you have created your own singleplayer or stand alone level, and want them in the mod manager, you can send it to them for approval.

 

Download the Mod Manager Here. (not working)