AdventureCraft, is a stand alone Minecraft mod designed to let players create adventure maps for other players. It allows you have full control of how mobs spawn based on the player triggering blocks with a custom trigger system. There is plenty of additional features as well to aid with making adventures that you can check out in the features section or the various youtube videos of features. I have included a small sample map showing off some of the early features.
How to instal AdventureCraft 1.4.5?
1. Download AdventureCraft for Minecraft 1.4.5
2. Install either via Install (copies the files from your minecraft directory) or Install Via Login (gets a fresh copy)
3. Press start, Enjoy
Download AdventureCraft 1.4.2 for Minecraft 1.4.5