It's hard to describe what is really Antichamber, mainly because it is in a constant change. What appears to be a room roughly delineated quickly becomes much more than that. The various colors draw the meaning that was not there before. Everything is much more than it seems at first glance. Nothing is what it seems in Antichamber and this becomes a much richer experience because of it. The similarities with Portal are more than many. Yes there GLaDOS and the graphics are completely different, but the bottom Portal is at the heart of the game and is the main inspiration.