> where precision matters (like train stations or airports).

That is true. That is called e.g. 'Bahnhofszeit' and follows different rules than normal time telling. You should include that in the game description, otherwise learners may think that is how you tell the time to each other in everyday life.

I think it is less about precision as e.g. 'zwei vor dreiviertel Elf' is as precise as 'zehn Uhr dreiundvierzig', but more about the way of measuring times. E.g. you do round normal time, but truncate 'train station time'.