InDungeons & Dragons, the rules of the game are at best suggestions that you may use to craft the best game for you and your table. While there is an infinite number of ways you can change the game, the Dungeon Master’s Guide offers a handful of alternate rules to choose from.
These changes range from adding a small bit of flair to your character or completely changing the pace and difficulty of the campaign. While any rule change is valid, some are useful enough that it is surprising they aren’t standard in the Player’s Handbook.

10Firearms And Explosives
Part Three: Chapter Nine
One thing many players don’t know is that there are official rules for all kinds of firearms and explosives for D&D Fifth Edition. This also includes hyper-advanced alien technology like laser pistols and antimatter rifles, the latter dealing up to 48 damage in one shot.
While most of the more advanced stats will likely never be used in your D&D campaigns, most of these new stats can be used to quickly advance your fantasy setting into a renaissance or even anold West theme. Just make sure to understand the increased scaling of damage for firearms and how it could affect power balance.

Most of these new weapons have a new reload property, which is different from the loading property on crossbows.
9Villanous Class Options
Part Two: Chapter Four
Two subclasses that are normally hidden from players are the Death Domain cleric and the Oathbreaker paladin. While these new subclasses are intended for Dungeon Masters to create villains with unique abilities, they can also be given to players.
For the Oathbreaker paladin subclass specifically, it can be a way to punish paladin players who break the oath in their original subclass. However, this should only be done if the player and DM agree to it beforehand. Although these subclasses are flavored as being for evil characters, you can easily use these abilities with any alignment.

8Madness Table
Part Three: Chapter Eight
One of the best ways to introducesuspense and horrorinto a campaign is with the madness table. The Dungeon Master’s Guide splits the table into short-term madness, long-term madness, and indefinite madness. Madness can be caused from any reasonable source and requires a saving throw to contest.
While the short-term table is mostly for role-play purposes, long-term and indefinite madness can seriously affect your character and even completely change their personality. Madness is an excellent optional rule for horror campaigns or if the players favor a style of game with heavy roleplay.

You can also add the optional ability score, Sanity, if you want to play a game with more eldritch themes and Call of Cthulu vibes.
7Starting Equipment At A Higher Level
Part One: Chapter One
One of the more popular decisions in modern D&D is to start a new campaign at a higher level, usually three or higher, to get past the less exciting adventures. However, it should make sense that a higher level adventurer would have access to better gear and more coin than your average level one fighter.
With the Tiers of Play optional rules, there are specific equipment packages depending on what kind of campaign the character is in. While most levels just grant a large amount of gold, higher magic systems allow players to pick magic items, which can also help a character feel more unique without the experience of previous sessions.

6Proficiency Dice
While most optional rules attempt to speed up gameplay or simplify it, the Proficiency Dice optional rules can add additional rolling, but can lead to more intense and exciting moments. The main change this rule makes is replacing the proficiency bonus with a die roll that scales up as you level.
While this means you have to roll twice as many dice on a skill check, it can lead to both higher and lower than normal rolls. It makes certain checks less reliable but can also have very high rolls that feel much more spontaneous and interesting.

5Background Proficiency
Another optional rule for proficiency, Background Proficiency removes automatic skill and tool proficiencies and instead relies on thebackstory of the character. What this means is, if you think your character would reasonably know how to accomplish a specific task, you can argue for proficiency.
The main problem with this rule is that players might start arguing for proficiency on every roll they make, but in honest games, players can more deeply connect their characters to the stats on their sheets. It can also remove the problem of trying to plan your proficiencies before the start of the campaign.

4Gritty Realism Rests
Another change modern D&D campaigns tend to make is stretch out the daily encounters so that the players can get to the meat of the campaign faster. One issue this creates is that players never have to worry about their class resources or spell slots because they get them back after only one or two combat encounters.
Gritty Realism Rests makes the simple change of having short rests take eight hours and long rests seven days to complete. With this change, you don’t have to slow the game down with the suggested eight encounters per day and make traveling more of a challenge without adding constant danger.

To balance this with magic items, make them regain charges after seeven days, instead of after one.
3Initiative Variants
The Dungeon Master’s Guide offers a handful of variant rulings to initiative and all have their merits depending on the preferred speed of combat. The best ruling for the quickest initiative is by having a standard Initiative Score, which automatically determines your initiative roll, similar to Passive Perception.
On the other side of the spectrum, with the Speed Factor variant rule, each member of combat declares their actions and rerolls initiative every round, subtracting or adding to the roll based on a modifier table. While this can make combat almost unbearably long, it makes it as fair and unexploitable as possible.

2Injuries
One of the more interesting and realistic rule variants is the Injuries tables, which can permanently damage characters until they use high level healing spells. These can be from simple scars to a lost eye and even lost limbs.
The book suggests multiple ways to trigger a roll on the injury table, but the best suggestion would be to give it to any character that receives more than half of their maximum hit points worth of damage in a single attack. However, this rule only works if everyone at the table agrees to it before their character is permanently blind.

1Cleaving Through Creatures
One of the most important parts of designing encounters is adding plenty of weak monsters that are only meant to slow down the party and force them to use resources. At higher levels of play, it can feel dissatisfying to deal 40 plus damage in a single blow to a goblin with seven hit points and still have ten left to fight.
With the Cleaving Through Creatures optional rule, if you kill an undamaged creature in one blow, the excess damage transfers to another undamaged creature within melee range, and so on. By adding this rule, DMs can also have the excuse of adding a high number of weak enemies without worrying about combat speed.