This heuristic obviously doesn't work. I build a factory in a strategy game. It is going to take 10h. The timezone shifts; should it take longer, shorter, the s

This heuristic obviously doesn't work. I build a factory in a strategy game. It is going to take 10h. The timezone shifts; should it take longer, shorter, the same? Obviously the same. You still need to use your brain and careful UI design. Things that a user scheduled to happen at a specific local time need to store the relevant timezone, implicitly or explicitly.