THE latest video issued by embattled terror group ISIS shows young boys being forced to shoot prisoners in a barbaric real-life Call of Duty game. Young children are forced to move room to room in a disused warehouse as they hunt down handcuffed prisoners of the terror group.In scenes too distressing for The Sun to show in full, the boys open fire and kill the men in cold blood. They roam room-to-room in the style of computer game Call of Duty as terrified prisoners beg for their lives before being callously gunned down. The latest sick stunt by ISIS comes as it emerged the self-declared caliphate is struggling to pay its warped fighters. Iraq's former finance minister Hoshyar Zebari told Sky News the group is fast running out of cash. It had previously made up to £4million a day from the oil-rich lands it held in Iraq. But after setting fire to oilfields in a bid to ward off air strikes with thick black smoke, that source of income has dried up. Zebari said: "They were taxing every business - they were taxing every shop, every pharmacy, every activity - not to mention the money they stole from the Iraqi banks. "They were a very, very rich organisation. Now, I think they are on the retreat and they are broke. "Also they are losing ground, so this battle in Mosul is decisive to end their caliphate - to end their so-called Islamic State." The latest 'Cubs of the Caliphate' video is one of dozens used by ISIS that shows children being brainwashed and forced to perform executions. Several have seen kids told to execute 'spies' at point-blank range.