Not saying its out of the question, however,
We've thought about mines, and are having a hard time deciding how they would be implemented.
If they're invisible all the time, people just randomly die (not fun), if they're invisible up until a certain point (so you could still turn away), this point becomes a hassle to manage. As people with low pings (wifi, and some on 3g) will see them, and be able to respond quicker. Where people on edge may see them, and not even be able to turn around in time. If they're shown early enough (from far enough away), you'll never kill anyone.
Again, not saying its not possible, just saying it becomes very difficult to design fairly
