The Rogue in Dungeons & Dragons™ 5th Edition (5e) is the current evolution of the original Thief.
The Thief class was first seen in the 1975 Greyhawk Supplement which was inspired by the works Fritz Leiber Fafhrd and the Gray Mouser and Robert E. Howard's Conan - as both author's works were named in the now infamous Appendix N.
After the supplement's release the class was quickly graduated into a core D&D class, alongside Fighting-man, Magic User, and Cleric; as evidenced by its inclusion in both the Moldvay edited Basic Dungeons & Dragon™ and Gary Gygax's Advanced Dungeons & Dragons™ 1st edition (1e).
As a class the original Thief was weak in combat with a d4 hit dice, leather armor, but could use all weapons (Moldvay Basic). Gygax had is as d6 Hit Dice, leather armor and shields, and most weapons. And over the first 30 years, the class stayed pretty steady.
The Thief had some skills such as hide in shadows, move silently, climb sheer surfaces, and hear noise that were interesting but not unique, as most are also seen in the Ranger and Monk/Mystic classes.
The Thief did ascend levels fast - twice as fast as a Wizard - but they often died much quicker too, and it had no spellcasting ability.
What made the class unique however was its special attack called back stab, and its two exploration skills pick pockets, open locks, and disarm traps.
To do a back stab the Thief needed to sneak up on their target and attack from a unseen position.
A successful back stab was initially +4 to hit and double damage. In AD&D this changed to be a progressive multipler, building from x2 up to x5 at level 20.
In either case, getting a back stab was something really terrific. It happened rarely, and when it happened the player was rewarded with their moment to shine in the limelight.
What made the back stab great was that the player had to play differently in combat, they had to play smart! Hence why it really was an advanced character class.
The other unique abilities of pick pockets and disarm traps gave the Thief a role and their own mechanics in the flow of play outside of combat. In essence, they became a required party member for exploration of a dungeon and seeking treasure.
What's remarkable about the Thief in its design and inclusion in the game is the impact that it had. It was the first clear signal that D&D was more than a tactical skirmish simulation wargame rule set - more inline with Dave Arneson's novel idea of role playing.
In 3rd Edition (3e) the Thief became the Rogue, the back stab was enabled simply by flanking, and the multipliers when in favour of a +1d6 to damage for every 2 levels up to 10d6. The whole game jumped in complexity and scale with lots of hit points, huge bonuses, et al.
Now with the Thief linage understood, it becomes easier to see that the Rogue in 5e is not the Thief. The Rogue is a skill specialist class - a chasis that you can make a thief from. If spellcasting was a skill you could make a Druid from it too. And if striking vitals from flanking really was so damaging then battlefield evolution would show that every fighter would learn the sneak attack skill.
My point is that the Rogue is a structured to be a specialst class in 5e, but one with a spefic Thief skill. The game design interest here is the question of where one draws the line between class abilities and generic skills.
The changes I would make to the 5e Rogue to make it a class again - instead of a chasis - are relatively easily done at 1st level.
Hit Dice. D6
Weapons. Simple weapons, short sword, scimitars, rapiers, blow guns, long bows, and heavy crossbows.
Armor. light armor and shields.
Tools. Tinker Tools, Thieves Tools
The Hit Dice change is to reflect that rogues avoid combat in every possible way shape and form. They don't develop combat skills, they instead develop avoidance skills. If you want a specialist dexterity combat character, use the fighter class.
The weapon change is simply to include the blow guns, all bows and crossbows. Note I also remove the hand crossbow. This is a naturally a setting thing but do your own research: for me a thrown knife had a better range and more penetration that a pistol/hand crossbows; and Black powder weapons would arrive before a more effective hand crossbow was engineered. And in your world, if gnome tinkers make a clockwork hand crossbow then fine, just in my worlds I call those magical weapons or special weapons by artificers.
Also, I include armor here simply to note that I let all classes use shields. I think it's a skill similar to simple weapons, in so much as it should be available for all characters who have simple weapons, as a villiager or a peasant can still use a shield.
Tinker Tools - a direct renaming for 5e Thieves Tools - are pliers, tension bars, lubrication and acid, eye dropper, etc for opening locks and working with mechanical traps.
Thieves Tools - are finger blades to cut a purse, hidden pockets for quick stashing, dark cloak for hiding, shadow grease to stop skin reflections, silk wraps to silence your equiplent etc
Trapcraft. At 1st level you have learned the ability to find and sense traps. When you use an action to examine an object or area you can make a d20 Test and add your Intelligence modifier. If you have Tinker Tools you can also add your tool proficency bonus.
If the object or area examined includes a trap trigger or trap area of effect, and your result is equal or better than the trap DC you detect the trap.
If your result is 5 or more better than the trap DC you also get advantage to disarm the trap. If you roll a natural 20 you get advantage to disarm the trap and advantage on any saving throws if the trap is triggered.
When using Trapcraft to examine an area, the size of the area is 10 feet x 10 feet multiplied by your proficiency bonus. Examining an area with many objects within it typically requires 1 minute. Disarming a trap typically takes 1 minute.
Additionally, trapcraft works like a sixth sense in that it provides a passive sense ability equal to 8 + your intelligence modifier + your proficiency bonus. Any trap with a DC equal or less than your passive trapcraft is sensed by you before you enter the traps area of effect. You know a trap is present but not where it is unless you use an action and pass the d20 Test.
At 6th level your Trapcraft ability works for magical triggers and magical effects.
Have you noticed in 5e there is no specific skill to find traps. Even if you cast the almost uterly useless Find Traps spell, you only know if there are traps present, and not where they are or how to find them. And defering to the Investigation skill - or worse the Perception skill - makes no sense as they are generalist skills. To fix this strange omission I propose Trapcraft.
This skill makes traps more interesting and gives a role to the rogue character outside of being a sniper.
Also, as an aside I suggest you hack the Find Traps spell so that is magically shows trap triggers and area of effects to the spellcaster. This will at least make the spell usable in the game rather than useless as it is now.
Sneak Attack. Beginning at 1st level, you know how to strike subtly and exploit a foe's distraction. As an action on your turn you can make a sneak attack. Your sneak attack must be from a hidden position using a light melee weapon or a bow or cross bow. Being hidden gives your attack advantage. A successful hit means you can add your a number of D6 dice to your weapon damage equal to your proficency bonus. If your attack is a critical hit, you also double your sneak attack dice.
This design makes the Sneak Attack happen less often as it requires an attack from the hidden position - inline with the original theif class. Hiding isn't something you can do in plain sight, and flanking no longer being enough, such a edit will totally changes the combat behavior of the Rogue class. In short, they are no longer heavy hitters doing a sneak attack every round.
It does however make the halfling Naturally Stealthy and wood elf Mask of the Wild abilities much more interesting however.
Also reducing the damage from 10d6 to 6d6 is because I prefer a scaled down game: Less hit points; less bonuses to attack, skills, and saves; and more tension.
With the One D&D changes to feats, it's likely that the Sharpshooter feat will get pushed back to a Tier 3 feat. This will be a welcome change in my opinion as it steals the limelight from many character abilities - such as sneak attack - at the moment.
The recent One D&D Unearthed Arcana suggests a change to tool proficiencies - that you can add your proficency bonus twice to a skill if you also have a proficient tool for the job. I figure that expertise is kinda moot now. Sure this rule means tools will be used more often, but its sadly another power boost to an already modifier rich system.
Consider a character with skill expertise and using tools - at 1st level a normal bonus might be Ability modifier +3, Skill proficiency +2, Expertise +2, Tools +2: is a total of +9. At 5th level this is +12! This makes the d20 Test just basically irrelevant.
Also adding Tinker Tools (open locks, disarm traps) and different to Thieves Tools, the Rogue effectively gets expertise across both pick pockets and stealth, as they can add their proficiency bonus twice to their d20 Test from level 1 when using tools.
However, Expertise is also at 6th level...
It seems fitting 6th level to insert another Rogish Archetype Feature. This fits perfectly well, as the current 5e Rogue lacks any type of subclass definition between levels 3 and 9 currently. Level 6 is in the middle and a suitable spot to add flavor specifc sub class feature.
Blindsense. At 2nd level if you are able to hear, you are aware of the location of any hidden or invisible creature within 10 feet of you.
At 14th level your Blindsense range becomes 30 feet.
Of the other 5e abilities of cunning action, Steady Aim, Uncanny Dodge, Evasion, Reliable Talent, Blindsense, slippery Mind, Elusive, and Stroke of Luck, are fine.
To really settle exploration into the fiction I also suggest that you add the Appraisal skill. An Intelligence skill which allows you to determine the approximate worth of an item or treasure.
I think this hack helps add a relative value for items in the world. I include this here because I think the Appraisal skill would be a natural fit for the Rogue, and in particular for a Thief subclass. A wizard surely doesn't care to understand the petty value in gold of mundane items, nor a Cleric, but a fortune hunting fighter might like the skill. And surely a Thief, as it's their jam!
So in all, only some subtle changes here at 1st level of the class:
- Sneak Attack: changed to be more of a hidden attack (aka back stab),
- Trapcraft: to make the class fit for dungeon exploration, and
- Thieves Tools: repurposed to be for pick pocket and stealth.
I added Blindsense at 2nd level and extended at 14th level to 30 feet.
And at 6th level added a much needed Roguish Archetype feature,
These hacks are all about returning the Rogue class back to fulfilling a role in the exploration pillar. If Wizards of the Coast want a specialist warrior then make it a fighter. Or use the Sidekick - Expert character class from Tasha's Couldron of Everything - page 142.
A character class with Sneak Attack will always be a thief in my books.
And that's it for my thoughts on the Rogue.