In a 'fail forward' paradigm, not being able to open the door gets you (with some added difficulty/consequence) to where getting through the door would have (for instance, while you're unsuccessfully tyring to open the door, an enemy patrol you were hoping to avoid comes through it, and you have to silence them quickly or the jig is up).
This is another example of terminology drift.
"Fail forward" is a technique that was championed by certain indie designers. The 13th Age rulebook (p 42) describes it thus:
A simple but powerful improvement you can make to your game is to redefine failure as “things go wrong” instead of “the PC isn’t good enough.” Ron Edwards, Luke Crane, and other indie RPG designers have championed this idea, and they’re exactly right. You can call it “fail forward” or “no whiffing."
In Luke Crane's Burning Wheel ruleset, it is elaborated in this way (Gold edition, pp 31-32):
When the dice are rolled and don’t produce enough successes to meet the obstacle, the character fails. What does this mean? It means the [player's] stated intent does not come to pass. . . .
When a test is failed, the GM introduces a complication. . . .
Try not to present flat negative results - "You don’t pick the lock." Strive to introduce complications through failure as much as possible.
As Luke Crane presents it, the
forward in "fail forward" is not
that the PC gets to go forward in the desired direction. It's that
the events of play keep going forward, although in some way that is at odds with the player's intent in having declared the action.
In the 13th Age rulebook, the description of "fail forward" goes on:
A more constructive way to interpret failure is as a near-success or event that happens to carry unwanted consequences or side effects. The character probably still fails to achieve the desired goal, but that’s because something happens on the way to the goal rather than because nothing happens.
The idea of "fail forward" as "near-success", or "success with complications", has become increasingly common. In this variant usage, the
forward is precisely that the PC gets to proceed in the direction the player hoped. Whereas the Luke Crane-type "fail forward" is a technique that is intended to support player-driven RPGing, by substituting
dramatic outcomes of player-delcared checks for a GM pre-authored storyline. But the more recent, and increasingly common, "success with complications" notion of "fail forward" is a technique for facilitating GM pre-authored storylines, by ensuring that no "unpassable" obstacles get in their way.