I wanted to touch on Limits, one of the new game mechanics in Shadowrun 5th Edition. Limits are used for every test in Shadowrun. They provide a hard limit for the number of successes that can be applied to a test. For example, in 4th Edition, if a player wanted to fire a pistol they would roll their Reaction + Pistols, and would apply the hits they rolled to the damage of the pistol. This works great, but it allows a few strange scenarios.
Let's look at an example. With a Agility of 6, and a Pistols of 6, the player is rolling 12 dice. Assuming one third hit, that's 4 successes. That's enough to take a hold-out pistol up into one shot, one kill range. Which, makes sense for a highly skilled user, even if it is a little off putting. Now, as I'm sure anyone who's ever rolled dice knows statistics mean little in the real world. Let's take that same test, and assume the player rolls really well, with 8 successes that same hold-out pistol has now shot up into combat rifle damage. That just doesn't make sense. This is where limits come in, and really shine.
Every test, every piece of gear, has a limit. For firearms it's accuracy, for active skill checks it's a calculated limit using your attributes. In our hold-out example above the accuracy of the firearm is a 4, or 5, depending on the model, that means that the player can use at most 4, or 5, hits. Granted there are ways to get around this using Edge, another game mechanic that we'll go into later, but for most tests you're stuck with your limit.
For gear this enforces a sort of "state of the art" mentality, as your character improves, you'll find you're losing more and more hits to your gears limits. This encourages players to update their gear, to purchase equipment, and cyberware to push those limits even higher, or to simply accept that the amount of damage they can do with their bargain basement Street Sweeper shotgun is sadly, limited.
Limits also effect skills, in fact limts apply to nearly every skill test. Skill tests in Shadowrun 5th Edition are limited by a calculated maximum based on a players attributes. Let's look at an example I've seen time, and time, again. Take your average magic user. Nearly every player I've seen builds a mage, and uses the physical stats as their dump stats. Body, I don't need no stinking Body! In 4th Edition this was safe, you could get away with having a few dump stats, without too much pain. But, in 5th Edition, with limits, these dump stats hurt, a lot.
Let's assume the following spread: Body 2, Reaction 4, Strength 1. Our mage knows that he might have to move, and needs to be able to react, but he's not terribly worried about his body, or strength, he has hulking Street Samurai to absorb bullets, and spirits to do the heavy lifting. How does this effect his Physical Limit? It's a 3 folks. That means, for any physical test he can apply no more than three successes. Want to climb a rope? Want to scale a wall? Want to simply run away? Hope you don't need to swim.
Limits don't prevent you from performing a skill, they simply prevent you from performing a skill well. Our mage above, with a Climbing skill of 12, and a Strength attribute of 1, the player is rolling 13 dice. Regardless of the number of successes they can use at most 3 hits. So, he can climb, but he's not climbing quickly, or with any grace.
Limits provide an effective method of limiting end-game power, veteran characters become more and more reliable, able to pull of dangerous, or highly technical actions reliably, yet they can't simply walk through a platoon of enemy guards, even with all the dice in the world, they are still limited by their own bodies, and the quality of their gear. As a GM, this opens up a much longer campaign view.