Personally, I don't think the reference to heavy rain has anything to do with the game. The 2 writers, Mark Gatiss and Steven Moffat, came up with idea whilst talking on the train coming back from Cardiff to London. They have both been writers on the Doctor Who series and seeing the murder victim was a television executive who had a whole string of lovers, I suspect the whole thing was a joke at the expense of the Dr Who production staff. The writers are an Englishman and Scotsman poking fun at the welsh Cardiff for raining all the time. Sorry no games involved.
Edit: Oops I forgot to explain the scene that mentions heavy rain was Sherlock explaining the that murder victim had just come from Cardiff to London on the train. He worked it out due to that fact the only place in range that had heavy rain was Cardiff.