They can also follow you around the map, but they will always remain in their maps. The NPC's scripts are very plain as all they can currently do are appear and disappear at certain times of the day. You can change their body types and clothes freely. You can basically run around with the main girl and have sex with her and the NPC's.
There isn't much to do at the moment since it is still very new and not a lot of mods exist. This game is basically just a sandbox that takes most of its direction from 3D Custom Girl and Artificial Girl 3. You can help the Hgames Wiki by expanding it.