We played MoM last night for the first time.  Awesome game.  

I am curious - anyone try playing with the rooms covered at the beginning?  Seems like that would add to the dread and mystery of it, and avoid that "run to the rooms with locks" for good stuff mentality.  You could even add a few scattered monsters underneath some covered rooms that get revealed once a room is opened (just the monster card obviously).  

Any reason why this would or wouldn't work?

You could cover a room until someone goes to a door and reveals it.  Maybe then hide a "map" token somewhere as well that can reveal the whole map to speed things along towards the end. 

Thoughts?

This would not be a good idea. Some reasons that come immediately to mind are:

1. The game's already hard enough for the investigators
2. Their first hint is to go toward a specific room or area, and they can't do that if they don't know which way it is
3. Events sometimes place monsters in specific rooms
4. There are some randomly seeded cards, and that can be tricky to mess with when you have to set up a new room that does not have a set seeding
5. Remember that Lock cards are triggered when you try to enter a room, which means they're in an adjacent room. Trying to open a lock pretty much means you have to reveal the next room, even if you can't yet enter it.

In other words, while hiding the rooms may work well for theme, it will screw up gameplay too much. Better to just

Additionally, for the most part, scenarios do a good job in putting a fair number of monsters in. Adding roaming monsters would make the game way too hard for the investigators. You'd need some way to determine what appeared where, anyway.

Agreed. Dont bother with trying to cover or hide or remove the cards. They are best in place on the board. Not only will it complicate things for no real gain the cards are there for a reason. Right now it may look like a give away but its also helping set up the long con. Later, when you start making your own scenarios, you can use the set up to advantage in the form of red herrings.

As a side note.. I'd recommend the sleeves for the cards. They are great! Not only are you reducing wear and tear on the components that need it most you are also adding more plastic to your life!

Well, it is always good to have alternative view points, so here is mine. 

We have been playing with partially hidden map and cards in a port-folio for a while and it makes a much better game (by far !). 

It does surely increase the load of work for the keeper but it is definitely worth it. Hiding the map is the option that needs several minor changes in the game (like handling monsters in hidden tiles or guiding the investigator to hidden part of the map, etc) but at least removing the cards is easy and already makes the game more exciting. We use 3D doors (here) for all doors that have not been opened yet (each time one tries to open a door, ask the keeper if it is locked).

I suspect that most (if not all) players that defend the opposite never tried to play this way ^^. For some scenario the hidden map is tough to handle, for others it is simply very natural. So, everyone please try at least once and post your impressions afterward.