It's a concept taken from conversations held before I got the BCCS book in hand. I'm not sure if it's in the BCCS book as I use it, as I honestly put it into play before I got the book. I think they do it a little differently.
Anyway, the way it works is: During the surprise round, all successful attacks cause MDT saves. Which sounds very lethal (and it can be). But I have a whole passel of other rules that come into play here, as well.
One: MDT saves are DC 10 + 1/2 Damage. Because of my harsh encumbrance rules and the fact that Sneak Attack is such a high-level ability in GT, most stealy fellows seem to favor a knife/dagger for their wet-work, so the average save is somewhere in the realm of DC 11.
Two: I make Listen and Move Silently checks before deciding on surprise. A surprise round happens only when one side or the other is truly surprised. If you had to troop up two flights of stairs in plate, the guards aren't surprised. If you had to kick down a door, THAT happens on the surprise round, so you'd better hope Smashdor The Mighty brought it down with the first kick or they won't be surprised. Surprise, then, is usually reserved for the specialized rogue-like character who travels light and attacks from darkness.
Three: I don't roll initiative. We deal cards for all of our games, anymore. I've found it speeds up play dramatically (as nobody has to write down their initiative, it's right there). Each person is dealt one card for each 3 points of init bonus (or penalty). So, for instance, Bleda The Sailor has a 16 Dex (+3), so he recieves 2 cards during the initiative phase and takes the highest. Masterful Assasin Guy has Dex 18 and Improved Init (+8 bonus) so he is dealt 3 cards and can take the highest. The Incredible Lunk, on the other hand, has a massive 4 Dex (-3) and gets two cards, but must choose the lowest. (Taking the low card has occured once, when my assasins got the jump on some party members with Curare poison and one guy was slumping around a 2 Dex for a while). Certain cards do certain things: The Joker always goes first in a round and nets a "Free Virtual Action Point" for use in the round. The Suicide King goes on King init but all d20 rolls have a -2 penalty for the round. (I let people opt the other card if they're getting two cards). This really only comes up when I want to make for a dramatic moment and so I say the element of surprise was blown at the last possible moment (the last Move Silently check was bungled, but within partial charge distance, say) ... if the surprisee wins initiative, he is prepared and the stealth attack is ruined. I COULD say that it works on any flatfooted foe, but I've never liked the idea that The Incredible Lunk, acting last in the round, has been so totally flabbergasted for six entire seconds that he's going to get his throat slit or stabbed in the chest without recourse. Call it my "He Who Striketh First" rule, I guess. Dealing cards has some strange effects on initiative. Up until Dex 16, everybody has the same single card ... that 16 Dex provides a huge improvement, and alot of people shoot for it if they want to surprise people. Dex 14 and Improved Initiative works for this, as well, but I haven't seen anybody jump on it. A guy with 16 Dex gets the jump on a guy with 14 Dex very often.
This has saved their bacon before because Bleda (our fast and stealthy bloke) has several times lead the way into touchy situations and has been able to eliminate sentries and guards silently and quickly. Without this sort of rule, most situations like this (which are a fantasy and military drama standard) turn into flat-out combats or, somehow, the guy with the greatsword makes for better assasinating than the guy with the knife.
This has come back on the heroes as well and so far the players have liked it. Of course they've all got alternate characters and I've never put them in a situation where somebody was going to kill them outright if they failed the save. Drop them, capture them ... save them and eat them later, perhaps, but heroes need to be captured from time to time so there can be rescue missions.
--fje