For those who don't know, Adventurer, Conquerer, King System (ACKS) is like B/X D&D, though with a wonky attack system (I prefer 3e-style DCs for all that stuff, and yes, I have played ACKS as written). Whatever. The real kicker is that the authors (mostly Alex Macris) have gone out of their way to make a very cohesive system for campaigns, especially for hex crawls and setting up domains. Any game inspired by B/X (which is my favorite OSR D&D, though I use liberal amounts of AD&D as well) or an akin system can use this.
It's at about 70% and still has a month to go, so it will fund, barring a true disaster, so get in to preorder.