Slowly but surely!
I'm still taking this pretty casually, and I started the day off by starting a new project and porting what I had (which wasn't much, for better or worse) over to a fully 2D project, so I'm still not particularly far along. Initially I was going with a "2D in 3D space" approach, which I personally am fond of and more familiar with, but it was definitely going to cause too many problems later on.
I think going the full 2D route will make my life a lot easier if I actually reach the point of level creation, the tilemap system in Unity should make that much easier than trying to fiddle my way into functional 3D levels. Mind you I have very little idea how to make functional 2D levels either, but it seems more practical in the time constraints and it will certainly be a learning experience.
So my game is still extremely limited functionally, and it's... not the prettiest yet. I do hope to vastly improve on my 20 minutes of aimless pixel doodles, but hey, it actually looks vaguely game like now!
