Ashrem Bayle said:
The guard stood there, unaware of the rogue, looking out over the surrounding area. But what could the rogue do? His only option was a sneak attack. So he did it, inflicting a nice chunk of damage. But the guard wasn't killed, and on his next action, he rang the bell.
The player became very frustrated, and rightfully so. The guard was a mook. A nobody. A "red shirt". But as we looked over his stats, there was no way the rogue could have eliminated him silently.
Put me down for a bit of bad DMing or bad player prep.
Bad player prep: The player sees himself as an invisible blade in the night... and doesn't pack a garotte? I don't care if he's not proficient in it: we're talking a flat-footed AC here and there's pretty specific rules for garottes that make them worthwhile in this exact scenario. (And ringing the bell while you're strangling to death? Any DM who makes his NPC do this on the very first action's going to have to have an awfully plausible reason.)
Bad DM: A guard in a tower for an army encampment has a very poor assignment: cold, high up in the winds, with minimal shelter, and massive boredom. This post is going to be handled by a Warrior 1 or a Warrior 2. If your PCs are going into or behind enemy lines, the PC rogue ought to be able to take down his man.
Let me revise that statement. At this point in that adventure, you should have started at 6th level and become 7th level (or 5th and 6th, but with modules you should always err on the side of caution.) So if he's 7th level, he should have 1d6 + 4d6 + STR + Weapon bonus: or 17 damage ON AVERAGE plus the STR and weapon bonus. (And that's assuming this alleged knife in the shadows PC is not packing Con poison or a garotte or a stone with silence cast on it by the cleric.) But even by the best case scenario, any warrior 1 or 2 in the world is going down after that.
Now, because it's a badly written adventure with a rigid DM, it's actually got 26 hp. So the PC has shivved him for 3/4 of his hit points despite everything going wrong from the player, DM and module author: wrong weapon, didn't take a round to guarantee the initiative win, no silence spell, no poison, failed the initiative roll, not a mook, and a DM who sent the wrong signals to the player.
[SBLOCK]
(Hint: if there's a dragon circling the area and it's the advance force of an army guarding a key maneuver point, it might not be a mook in the tower!) [/SBLOCK]
I mean, don't get me wrong: I hope GURPS or your system or whatever works for you and I'm sorry that you're obviously frustrated. But I'm going to have join the chorus that's chanting that the fault's in ourselves, not in the system on this one. That's not to say that you're right or wrong about the system, but the example you're using is not selling it for me.