If you want to be a good GM, one of the most important things you can do is learn to explain failure.
Player characters fail all the time. They try to leap onto moving horses (whoops, trampled), talk obstinate shopkeeps into extending small loans (taciturn glare, veiled threats to call the city watch), or bulls-eye small targets from improbable distances (miss miss miss reload miss miss).
Sometimes (rarely) players try things that just seem crazy, but usually they try to do things that they think their character can do. They are just trying to play out their character concept. Of course my pirate can grab a rope and swing over to the other ship — that’s what pirates do.
Then the dice get involved. Most games include a chance of failure because otherwise success isn’t very interesting. Where’s the challenge if there is no risk?
When a player tries to do something they think their character should be able to do but fails, it breaks their belief in their character concept just a little bit. Players love their characters (not your game) so if that fragile love between player and character is broken, that player will pretty much check out. Danger Will Robinson!
This happens in just about every game session in greater or lesser degrees. So how do you handle this perpetual problem? You guessed it, learn to explain failure.
Wait, what about explaining success? Don’t worry about it, it’s easy. If the players couldn’t imagine how they could succeed at something, they probably wouldn’t have tried it in the first place.
Failure should be big. As a GM the urge is to overlook failure, just nod at the bad roll and move along to spare the player the shame. Big mistake. The worst insult to a character in the game world is to have no impact. It’s better to screw up in a way that sinks the Titanic than to have no effect on anything (note we’re talking about the character screwing up, not the player).
When a character fails, emphasize it. Magnify it in the game world. Demonstrate that the character is having an impact, even if it’s not the impact they wanted. A missed energy blast doesn’t just vanish, it stitches a line across the building down the street, shattering windows and sending clouds of pulverized masonry into the air. The pirate doesn’t just jump and miss the rope, the entire boom snaps, sending rigging and sails cascading down on the deck of the ship and sending people running.
Big failure can leave a character more disadvantaged than a “let’s just pretend that didn’t happen” failure, but it puts the focus of the game on that character, which is what most players really want. Yes it’s a setback, yes the character is in a really bad jam, but the character gets the spotlight. Forget about hit points or mana or equipment: the only resource that matters in a game is play time.
The same applies to bad events the players have no control over like taking damage. When a character takes a critical hit don’t say “ooh, crit, 26 more damage, sorry dude” say “the wolf savagely rips into your arm, tearing at you with big sharp pointy teeth — take 26 damage” Part of that is just interesting description vs no-description, but part of it is emphasizing the bad instead of trying to gloss over it. Don’t apologize. The bad is the challenge. The heroes have to step up and deal with the bad. That wolf is going to freaking eat you man! You better do something!
When a character fails at something that (by their concept) they should have succeeded at, blame the situation, not the character.
Bad luck is your friend. Even the most capable characters can reasonably fall prey to the slings and arrows of fortune, so emphasize the circumstances, not the failure of skill. Make stuff up. When the pirate jumps for the rope, the pirate doesn’t just slip and miss, the rope or the entire boom arm snaps unexpectedly. When a macho hero is having trouble climbing a low wall, it must mean the bricks are crumbling in his hands, pebbles raining down in his face, whatever. It’s not that the character is incompetent, it’s just bad luck or unforeseen circumstances.
Or does the character have other traits that can explain the failure after the fact? If another important trait caused the failure, the concept isn’t damaged. The ace pilot rolls badly and wrecks his plane on a supposedly easy landing, but you remind everyone that the character is already known to be a reckless daredevil and probably tried something zany. He didn’t fail an easy task, he turned an easy task into a hard task (none of which is played out in the rules, this is just an explanation for the bad roll). Usually once you introduce a possibility like that the player will come on board and help flesh it out since you’re now re-describing what their character was doing.
Wait, you say, I’ve got a better idea! I’ll just always let the players succeed at things that are important to their concept. Genius! (No, I know you really didn’t say that, but as long as I’m writing this post I can set up all the straw man arguments I want.)
Some systems have this kind of “failure insurance” built into the rules. Spend a hero point to re-roll. Buy a feat that permit automatic re-rolls for things that are central to the character concept (Diplomats automatically get to re-roll low Diplomacy checks, just because they are good at it). Take 10. In other words, choose to neutralize bad rolls if they go against your character concept. I would say the trend has increased as some RPGs become more about character concept instead of tactical victory.
Succeeding when you expect to fail (or vice-versa) is part of the fun of gaming. It’s not planned creativity, it’s mob creativity reacting to random stimuli (the dice). Eliminate too much randomness, and you lose some of that magic ingredient.