Air Traffic Controller reported aircraft on visual approach losing sight of the airport resulting in the aircraft flying towards terrain. ATC issued go-around instructions to the aircraft.

Narrative

We were using the X [Runways]; advertising the ILS Runway XR. It was about half an hour past sunset. I had gotten on position a few minutes earlier and worked a few arrivals with no problems. Then I noticed Aircraft X approaching from the south for a right base visual approach to Runway XR; according to the scratchpad information in their data block.Aircraft X entered the surface area descending through 2000 MSL and turning somewhat east of the Runway XR centerline. As they descended through 1700 MSL the Low Altitude alert briefly activated and ZZZ Sector X called me to make sure I saw it. I responded that I wasn't talking to the aircraft yet and I did not issue an alert on my frequency. Aircraft X continued descending well off the centerline and was far lower than they should have been for a normal approach to Runway XR. When they were about three miles south of the airport I issued 'Aircraft X; ZZZ Tower; go around' with no response. I used the light gun to flash a red light at the aircraft although I doubt they noticed it because they were so far away from the airport.Aircraft X finally began to climb when they were about 2.5 miles south of ZZZ. ZZZ Sector X called to inform me that Aircraft X was still on their frequency; and that they reported they lost sight of the airport on the visual approach and were going around.The lowest observed altitude on the display was 1000 MSL which corresponds to about X00 AGL.Recommendation: Especially at night and especially in such a congested area; backing up a visual approach with some kind of electronic guidance would be a very good idea. If Aircraft X had loaded the ILS or the RNAV approach to Runway XR they would have seen that they were nowhere near the approach course. I'm not saying all visual approaches should start outside of the FAF; but at least having the electronic guidance visible would enable catching a misconception about where the airport/runway is.When the Low Altitude alert activated; I should have issued a safety alert in the blind; even though Aircraft X had not checked in on my frequency yet.