I've only played a very early version of Against The Wall, which presents an environment so empty that it's little more than a proof of concept, but it almost immediately wormed its way inside my head and it's now near the top of the massive list of things that I'm excited about and will furiously attempt to keep track of. It has a brilliant, somewhat Borgesian premise that it's hard to imagine in terms of exploration and navigation until you play it.
This world is an infinite vertical surface composed of irregularly-sized white bricks. Entire civilizations and ecosystems cling for survival on the side of The Wall, everyone and everything existing under the constant threat of tumbling into the endless sky.
Doesn't that sound absolutely fascinating? There's a short trailer tumbling in the endless space below and you can download the alpha here.
The shape of the world may be a stroke of mad brilliance but thankfully developer Michael P. Consoli isn't entirely mad. He's also a clever sort, as evidenced by the thought that has gone into designing a game around the idea of an entirely vertical environment.
Instead of just falling off forever, the player has the ability to pull out sections of wall simply by gesturing toward them. The bricks that make it up vary in size and it's always possible to create platforms to travel to a point where steps can be formed. This is useful because the goal is to travel ever upwards, back to the home from which you have presumably plummeted.
The finished game should have plenty of environments to discover during the journey, whereas the alpha only has a couple of things to see, but the potential for greatness is certainly there. If you do try the alpha, and you should, make sure to fall at least once, if only to see just how endless that sky is.