The movie Cube, the TV show Lost and, Portal are all broken down and reassembled in CUBE, a Half-Life 2: Episode Two mod about self-assembling test chambers. Unsurprisingly, I spent a lot of time stuck, but in a good way. CUBE’s an odd one: accomplished and beautifully designed in most respects, but always on the cusp of crashing. Engine errors are as ubiquitous as new…