Credit to https://www.trueachievements.com/gamer/RuhanR
for the Xbox solution I based mine on.
Start any map and build a road on one side of the incoming highway for low-density housing zoning. I made the housing road about 30 squares long. Then on the opposite side I built the same length road and zoned some industrial and some commerical.
To make sure people moved in, I did put a wind turbine and water/sewage lines through.
After all zone squares were full, I dezoned industrial and commercial and demolished those two zoned buildings, leaving housing as-is. I also turned off the wind turbine and water/sewage plants.
You can watch the happiness drop in the Info Views (
), then 2nd column, 4th row with the green smiley face. As soon as residential happiness hit 12% for me, trophy popped.