Tricks from Trail of Cthulhu

As with all GUMSHOE games, in Trail of Cthulhu random luck can't prevent the players from finding the important clues. All purely-investigative skills are 100% error proof. If you have just a single level of Evidence Collection, you will automatically spot the spatters of blood behind the sofa left over from the otherwise cleaned murder scene. With even 1 dot of Cryptology, you will eventually break the cypher. I like this approach, as it prevents one bad die roll from collapsing an entire plotline. Randomness is good and fine for fight scenes and incidental subplots, but when it comes to major clue-finding, GUMSHOE doesn't mess around.

There's even this sidebar on page 56 where they present the option of doing this with everything important:

Let's say your plotline hinges on the PCs getting onto the enemy base, which is guarded by a steep wall. Most games would provide stats for climbing the wall (and some would add details for knocking a hole through it). Nearly all RPGs would couch it as some sort of difficulty, and if the PCs failed to roll well enough, they'd be stuck (or, perhaps, they could annoyingly roll again and again until they succeeded*). What's more, the stats of the wall would be based on it's height and surface (for climbing) or thickness and material (for breaching it). That leaves a GM in a spot where he may have to fudge in the PCs favor, or at least provide an opportunity for the players to go fetch a ladder.

Trail of Cthulhu suggests that's entirely the wrong way to go about it. Difficulty shouldn't be based off the composition of the wall. Nor should it scale up with character level. Difficulty should instead scale inversely to the dramatic necessity of the task. If the PCs have to get over that wall in order for the plot to continue, climbing the wall should be automatically successful. If, on the other hand, there's more than one way to access the base, and those ways are built in to the scenario and/or addressed by the author(/GM) ahead of time, then it's okay to make some (not all) of the access modes more difficult.

They suggest not making the roll involve getting over the wall at all (that's guaranteed) but instead making "failure" on the roll mean you still succeed, but there's some negative side-effect doesn't stop the plot in it's tracks. Perhaps you're injured in the process of successfully climbing or you make enough noise descending the other side to attract attention from guards a few seconds after you make the guaranteed ascent.

The idea is this: Outside of major (non-trivial) combats and the climactic final scene of the adventure, player success should never be jeopardized by something as uncontrolled as the dice. Players can still fail by making wrong decisions. Players can still fail due to bad luck in the final confrontation. But no random nameless guard or 50 foot wall should be the source of the PC death or critical mission failure. That's a simple concept (and one I've used before without really thinking too heavily about it) but it's rare to see that appear in writing as a philosophy behind scenario design.

Kudos to Kenneth Hite and Robin Laws for putting that in words in a game that still has dice-based mechanics. Previously, I'd only seen such blunt statements in entirely diceless games. GUMSHOE is a happy medium between gaming paradigms.