Drools and Java can work together. Java and Minecraft work together. The obvious next step is to get Drools and Minecraft to work together.
The plan is as follows:
--A Minecraft mod boots up a list of Drools rules. These are either stored in a predetermined directory, or listed in a config file.
--Minecraft does it's start-up routines. The user loads a world.
--Each tick (world update) (or X ticks, determined by efficiency needs), the mod executes the rules.
--The rules call functions in the mod's Drools API. This is where the majority of the work will come in—I'll have to write a largish set of functions for drools to use. The functions will take two shapes: returning boolean values for tests, or acting upon the world.
--The mod reacts to the function calls, altering the world...
–...which the user then interacts with.