Yeah. The DM’s guide already provides some possible options here for games that want a little more to the melee attacking world than just “I swing, I miss, he swing, he hit.”
Action Options
This section provides new action options for combat. They can be added as a group or individually to your game.
Climb onto a Bigger Creature
If one creature wants to jump onto another creature, it can do so by grappling. A Small or Medium creature has little chance of making a successful grapple against a Huge or Gargantuan creature, however, unless magic has granted the grappler supernatural might.
As an alternative, a suitably large opponent can be treated as terrain for the purpose of jumping onto its back or clinging to a limb. After making any ability checks necessary to get into position and onto the larger creature, the smaller creature uses its action to make a Strength (Athletics) or Dexterity (Acrobatics) check contested by the target’s Dexterity (Acrobatics) check. If it wins the contest, the smaller creature successfully moves into the target creature’s space and clings to its body. While in the target’s space, the smaller creature moves with the target and has advantage on attack rolls against it.
The smaller creature can move around within the larger creature’s space, treating the space as difficult terrain. The larger creature’s ability to attack the smaller creature depends on the smaller creature’s location, and is left to your discretion. The larger creature can dislodge the smaller creature as an action—knocking it off, scraping it against a wall, or grabbing and throwing it—by making a Strength (Athletics) check contested by the smaller creature’s Strength (Athletics) or Dexterity (Acrobatics) check. The smaller creature chooses which ability to use.
Disarm
A creature can use a weapon attack to knock a weapon or another item from a target’s grasp. The attacker makes an attack roll contested by the target’s Strength (Athletics) check or Dexterity (Acrobatics) check. If the attacker wins the contest, the attack causes no damage or other ill effect, but the defender drops the item.
The attacker has disadvantage on its attack roll if the target is holding the item with two or more hands. The target has advantage on its ability check if it is larger than the attacking creature, or disadvantage if it is smaller.
Mark
This option makes it easier for melee combatants to harry each other with opportunity attacks.
When a creature makes a melee attack, it can also mark its target. Until the end of the attacker’s next turn, any opportunity attack it makes against the marked target has advantage. The opportunity attack doesn’t expend the attacker’s reaction, but the attacker can’t make the attack if anything, such as the incapacitated condition or the shocking grasp spell, is preventing it from taking reactions. The attacker is limited to one opportunity attack per turn.
Overrun
When a creature tries to move through a hostile creature’s space, the mover can try to force its way through by overrunning the hostile creature. As an action or a bonus action, the mover makes a Strength (Athletics) check contested by the hostile creature’s Strength (Athletics) check. The creature attempting the overrun has advantage on this check if it is larger than the hostile creature, or disadvantage if it is smaller. If the mover wins the contest, it can move through the hostile creature’s space once this turn.
Shove Aside
With this option, a creature uses the special shove attack from the Player’s Handbook to force a target to the side, rather than away. The attacker has disadvantage on its Strength (Athletics) check when it does so. If that check is successful, the attacker moves the target 5 feet to a different space within its reach.
Tumble
A creature can try to tumble through a hostile creature’s space, ducking and weaving past the opponent. As an action or a bonus action, the tumbler makes a Dexterity (Acrobatics) check contested by the hostile creature’s Dexterity (Acrobatics) check. If the tumbler wins the contest, it can move through the hostile creature’s space once this turn.
Things like called shots (in the vein of the “Weakening Strike” and “Crippling Strike”) are also an incredibly common houserule at a lot of D&D tables. My CoS GM, for instance, has the following house rules for our game that make things pretty fun!
General Rules
Advantage and Disadvantage: In general, if there is more advantage or disadvantage than its opposite, we will apply the advantage or disadvantage as the majority decides. For instance, if someone is grabbed, blind, and flanked, a rogue attacking them has advantage, even if they are sick to their stomach.
Targeted Attacks: When attacking a specific body part or item such as a sword, if it’s easy, then it’s a -2 to the attack roll, if it’s difficult then the attack is with disadvantage, if it’s hard it’s a -5, and if it’s nearly impossible it will be both with disadvantage and a penalty.
Inspiration: A player can have more than one inspiration point at a time. They function like hero points from Mutants and Masterminds. They can be rewarded for great moments of roleplaying, or, when your chosen traits, such as your ideal, become a defining moment.
You can have up to 3 Inspiration Points.
Feats: You are allowed to purchase feats when you would receive an ability score increase.
Critical Hits: With a critical hit you can apply a cinematic effect such as targetting a specific limb, causing a cool effect to happen, or doing damage to weapon, among other effects if you desire.