Inertial confinement fusion works just fine if you are building a 1 megaton device driven by a fission bomb. You probably can't make it work if you're driving with a laser because the wallplug efficiency of a laser is terrible, but at least you can build a failing facility which is only huge as opposed to gargantuan. Real breakeven might be possible with heavy ion beam ignition but the minimum size facility to make an attempt is gargantuan.