The first thing I needed to add for the side project was arbitrary collision mesh support (as all of the old levels are built out of tiles with primitive collision volumes). It actually came together really quickly - less than a week start to finish. The only bit I haven't coded up yet is mesh-to-mesh collisions. But all the primitive-to-mesh code is in and seems both stable and quick. Here are a few screenshots of Milkshake running around on a mesh that I've exported straight out of Maya. You can now build any kind of environment you want and go exploring!
I needed something to test the collisions a little more interactively, and what better way than to equip my little cow with a large geometry-shooting gun! It obviously would have been a little nicer to capture a video of this (because it's strangely satisfying to blast a stream of random shapes out into the world), but hopefully the pictures give you a hint at how much my little cow enjoys his little Rambo-moment in the sun:
The only other thing of note is that, in preparation for the side-project, Ive refactored my code and directory structure to accommodate multiple games built on top of the same engine. Each game just pulls in the components they need, they can override specific interfaces (for example, put in a custom control scheme), and have their own set of assets and scripts.