I'd say don't try to be realistic. 'Frontier' was realistic and it was dull. Often games totally ignore real-world limitations to make for better gameplay. If characters responded exactly as they would in the real world, you won't get double-jumping platform romps nor anyone surving several whacks with a dwarven battleaxe!
Write a game that's fun regardless of whether or not it obeys Newton's or Einstein's aggravating limitations ;)
Write a game that's fun regardless of whether or not it obeys Newton's or Einstein's aggravating limitations ;)