Depends on what you mean by "totally changing the game"... any given tweak might be as little as decreasing all weapon ranges by half, or it might be as big as introducing QNP into the game... well, OK, I probably won't go with the full-fledged QNP, because that would really mess people up, if they were previously limited to 6 engines on a ship and suddenly they needed 8 just to make it move anywhere at all
Just don't make me come up with any more examples, you're running me out of ideas and the game hasn't even started yet!
I guess if the changes are small enough, though, then the players should just know to expect something out of the ordinary but not TOO weird to happen at that certain time interval
