So, what I’m currently working on is a bit of an undertaking, and it will hardly get used in ACE, but I think it should provide a lot of opportunity for future modders: it’s a generic entity connection service. This service won’t exactly “do” anything on its own: it merely allows you to specify ways in which entities can “connect” to one another, and then maintains graphs of those connections. However, you can then build other services/systems that make use of those connection graphs.
The specific one I have in mind for ACE is a “mechanical” system that allows you to translate mechanical power from something like a water wheel across axles/gears into something that can consume it, like a grain mill (having a water wheel power an enhanced workbench is something we’re currently planning for, if I recall correctly, the engineer in a town that selects a particular Tier 3 bonus). Could this particular objective be achieved in a vastly simpler way? Sure, but then the infrastructure wouldn’t be there for doing similar mechanical things. And it wouldn’t be there for doing other connectivity things, like, for instance, redstone.
If I succeed with this endeavor, ACE will contain an easily expandable system for using entities to create/translate/consume mechanical power (even if it’s only used for a handful of entities with limited interaction), as well as this system being an example for creating other systems that use the connection service.