Markeen - High-Order Chains

Today I finally hammered out an implementation of high-order chain awareness for Markeen's level generator. Its first results were extremely boring; it just generated levels either filled completely with one platform style's inner tile or as an empty space with point items strewn about. The problem was that I had confused the sign on the offsets after rewriting the scoring algorithm to examine faraway tiles. After fixing that, I got a level that was decent:

I then tried fiddling with different fill patterns without much success. However, after a tweak to the scoring algorithm to devalue candidate exclusions based on distance, Markeen produced one of its best levels so far:

I created yet another fill pattern, this time one that starts in the center of the level and spirals out. It's currently creating levels that are extremely messy, so I guess my only remaining areas of research are eager generation of rare structures (i.e. if placing this iteration's tile leaves only one candidate for an adjacent space, fill that too) and smarter erasure.