App of the week: 3 cert, Terry Cavanagh, iPad (also iPhone, iPod Touch) ****

What’s the difference between a casual and a hardcore game? After a few goes of Super Hexagon, it seems that difficulty is the deciding factor. This app game has gotten rave reviews and angry complaints; the set-up is simple, but it’s also mercilessly tricky and endlessly compulsive. You play a triangle in the centre of the screen, placed on an outer side of a hexagon. Bit by bit (and at alarming speed) walls close in, leaving little gaps. You must move the triangle left or right so you won’t get closed in. The graphics are functional but attractive, and the voiceover is sparse, giving one- or two-word instructions: “again” she snaps when you start, and “game over” she purrs when you die. With its clinical appearance, polished synth/grime soundtrack and straightforward concept, it feels at once like a modern game and one that could have been in an arcade machine 30 years ago. As the screen pulsates, it feels like your portable device is shaking, and the game is mesmerising, intense and insanely challenging.