So, one of the biggest hurdles with making a mod like Dear Esther in Source is the rather clumsy displacement system which is used to create terrain and smooth surfaces. To have pixel-perfect seamless and smooth terrain in Source I had to build my maps in a very unique, complicated and time-consuming manner. Everything has to align with each other and be built from adjoining quad faced brushes, if that doesn’t make any sense then maybe this image will:

By building the map in this way (previously mentioned here) it will allow me to have one large smoothly subdivided displacement which I’m sure you’ll agree is a lot more easier on the eye and simpler to manage. So far 90% of my preparation work has gone into this but hopefully it will be worth it! I want to get all of the tedious work out of the way before I move back to the UK so I can then concentrate solely on the art (and fun!) side of things.
As a side note some of you may be thinking all these displacements will be a crazy fps killer, well, to Valve credit one thing I will say is that displacements handle very well in Source. I recently purchased this nifty laptop so that I could benchmark on what is the equivalent of a mid-range gfx card (based on Valve’s Hardware Survey) and I got 250fps without any optimisation – very promising! My only hurdle could be vertex memory, but I’ll keep an eye on that as things develop.

I found this tutorial really good for understanding how subdividing terrain works: http://halflifestorm.com/?page_id=225 Hopefully it will help you out.
This makes me so excited to see a better, incredibly more attractive way to do terrain in Source. I’m running into a problem when trying myself however, and I was wondering if you would mind giving me some advice. What exactly are you doing to make this work? Whenever I subdivide I seem to get these strange “artifact” looking things sticking out from my displacements. Or faces disappear. Really weird stuff. If you wouldn’t mind explaining just a little more, I’d love to hear about how you aligned things and such. Source has so much potential and I LOVE your screenshots of your current progress.