When you try to describe the much-loved video game Lemmings, it sounds like a wind-up. It looked, if not bad, then wilfully basic even for 1991. But, released years before mobile phone games were a thing, it was nonetheless a fiendishly addictive game that feels like the spiritual precursor to the likes of Angry Birds. And it was manna to many, many kids like me, whose sole household computing device was a rubbish PC with a horrible four-colour CGA screen that basically couldn't play any video game of the time … except Lemmings! To mark 30 years since its release, Exient – current holders of the franchise – has made a YouTube documentary about it.