For years, I was a player under a variety of GMs, and the finally, I ascended to the other side of the screen. Fromm there, I started by looking at the GMs I'd played under, and came to a hard choice: I wanted to see what a campaign looked like with no fudging.

No last moments saves or bailouts, no NPCs who were un-statted that could totally trounce the party, everything above board. Well, at first it was...............................

a bit of train wreck, as a number of PCs died.

It might have ended there, save that one of my gamers' light bulbs came on. They'd just gotten used to a certain flow of game, and just needed to get out of the rut.

Suddenly, plans would start going, and the party's overall unity increased. They started digging in, and formulating new strategies. Combats became more tense, because even a kobold encounter could end up going south if they weren't on point.

Monsters that were cowards ran away (i.e. kobolds), creatures made use of all their abilities, and as the PC death rate increased, a rather interesting thing happened: They were more engaged, and started talking more in-character. Whole plots developed out of their own actions and interactions, and they felt like it was more about them than other campaigns had been.

The reach for magical items changed as well. All of the sudden, boots of springing and striding and rings of sustenance became of greater value than most magical arms and armor, because they removed impediments, or allowed greater tactical movement.

On my side, villains were made more sinister as I had to pull together in-game ways of doing what would normally have just been fudged by the GM. Instead of the party calling BS when I did something, they might say something like, "Wait, he shouldn't be able to do that."

Me: "I know, right?"

and the KNOW that I'm being serious.

My skills as a GM improved by the simple omission of the easy way out. If someone was at 1 hp, and got nailed with a massive crit, it went through, most likely killing them. If they found a weakness in one of my villains, and capitalized on it, they would win. Depending on the villain, however, there might be consequences and repercussions to just snuffing him like that.