Splash Damage

Don't you hate it when your opponent decides to rush you with a horde of mooks so that you have to aim and take out each and every one while they swarm you? That's what good old Splash Damage is for! Their swarms of disposable mooks are no match for a well placed artillery shell blowing them all to pieces.

Most weapons have to hit their target directly to be effective -- but some lucky few merely have to hit near the target since damage occurs in an area around their impact point. This Splash Damage usually represents explosives; it commonly applies to rockets and bombs, but can (and surprisingly frequently does) show up on more exotic and powerful weapons like BFGs and Energy Weapons.

Splash Damage is typically distance dependent: the closer you are to the hit, the greater the pain. Usually, such a weapon will also do a fixed amount of additional damage if it scores a direct hit. However, some weapons (such as grenades) deal out splash damage exclusively.

In contrast, an Area of Effect weapon has constant damage/effects over its footprint.

This quality usually makes a unit very valuable in RTS games, where even very weak attacks can be highly effective in the right circumstances or in sufficient numbers, because a particular unit or tactic involves tightly bunching up a cluster of units, meaning that even a weak attack does that damage to every single unit in the cluster, making it a rather powerful attack.

Related tropes include: Cluster Bomb, Area of Effect, Spread Shot, Hitbox Dissonance, Splash Damage Abuse. Frequently an effect of the BFG and Wave Motion Gun. Sometimes allows players to Rocket Jump. Often used for a Herd Hitting Attack.

Tabletop Games

 * Dungeons and Dragons in all its editions, and Pathfinder (basically D&D 3.75), both feature "grenade-like weapons" or "splash weapons" depending on the edition. These weapons are usually a case of the useless useful weapon, as their effects are often available by other means at lower cost and with more impressive effects. Direct hits did more damage. Pathfinder introduces the Alchemist class, which specializes in dealing devastating damage with these weapons. Some spells, such as various editions of Meteor Swarm, had a similar mechanic where a direct hit may disallow a saving throw or do more damage.
 * Many games use a mechanic like this for actual grenades or other explosive weapons, with a diminishing amount of splash damage based on distance to the blast. Notable in Shadowrun, The World of Darkness games, Paranoia, Deadlands, and dozens of others.
 * Warhammer 40000 in Fifth edition has this effect for Ordinance weapons which hit vehicles, as direct hits often are crippling, but hits where the center of the blast misses the vehicle represent the shell missing the target but the blast hitting the enemy. These are much weaker against vehicles and not as likely to take out the enemy.

Video Games

 * Starcraft features various units in both one and two, not including the powerful AOE spells.
 * Terran: Siege Tanks, Firebats, Raven's Hunter Seeker Missile, and nukes.
 * Protoss: Archons, Reavers, and Corsairs.
 * Zerg: Ultralisks and Lurkers.
 * War Craft has units and heroes that can do splash damage. The Orb of Fire also grants any hero using it splash damage.
 * Humans: Mountain King, Mortar Team, Gryphon Rider
 * Orcs: Tauren Chieftain, Tauren, Catapult/Demolisher
 * Undead: Lich, Meat Wagon, Frost Wyrm, Destroyer
 * Night Elf: Warden, Chimera Ballista/Glaive Thrower
 * Iji: Splash damage is the main exception of Friendly Fireproof - which comes in very handy in a Pacifist Run.
 * Valkyria Chronicles: Grenades deal splash damage, which makes them one of the only weapons that can easily hit more than one target. Their main use, however, is taking out sandbags so you can get headshots on the exposed troops.
 * Tower Defense Games: this is one of the common anti swarming-Mook towers.
 * Super Smash Bros: along side the various explosives there are some attacks that have hitboxes that extend farther than what you'd expect, and are capable of hitting multiple opponents. King Dedede's and Yoshi's ground-pound moves, for example, deal damage to people standing close enough to the point of impact, not just the ones that you land directly on top of.
 * Pokémon Black and White: A handful of moves were introduced that, in double and triple battles, deal normal damage to their target, as well as a smaller amount of damage to opponents next to the target.
 * In Pokemon Mystery Dungeon, the attack Splash has the user splash to an adjacent square and if they hit someone, it does five damage to both the user and the victim. Splash averts this in the main series by doing no damage.
 * Quake series: the rocket launcher. Against fast targets, it's actually more effective to aim at the ground near rather than trying to hit directly.
 * Doom: rocket launcher, same as Quake.
 * Unreal series: rocket launcher, flak cannon, bio-rifle, shock combo.
 * Unreal Tournament 2004: the Paladin's weapon normally fires an explosive shell but if fired while the Paladin's shield is up, the tank will release a fairly powerful shockwave that deals damage to and knocks back anyone nearby.
 * Plants vs. Zombies: has the Melon-pult.
 * Mega Man 4: to defeat Dr. Wily you have to use Drill Bombs. However the bombs themselves bounce off his ship. To win you must detonate the bomb before it hits so that the Splash Damage of the explosion hits his weak spot.
 * Wing Commander II and Wing Commander IV have the Mace, a tactical nuclear missile that can be used to take out groups of sufficiently close targets, detonated either by shooting the missile (WC2 or on command (WC4).

Wing Commander IV also has the Starburst and Coneburst missiles, which effectively act like player controlled grenades. As the names suggest, the Starburst's shrapnel field is omnidirectional, while the Coneburst's damage is aimed forward in a conical pattern. Unlike with the Mace, though, the damage is constant within the damage area.
 * In Team Fortress 2, the Soldier's Black Box and standard rocket launcher both deal impressive splash damage - the Direct Hit, however, is geared so as to eliminate it almost completely (except in relation to the Soldier himself for the purposes of Rocket Jumping). Splash damage is also the Demoman's bread and butter depending on his setup; stickies from the standard sticky launcher or Scottish Resistance and grenades from the grenade launcher or Loch'n'Load have impressive blast radii.
 * The Demoman actually has as MELEE WEAPON that deals splash damage (a WW 2 stick grenade he is using as a club), that can kill most of the classes in a single hit and does damage to himself.
 * Water Warfare's buckets and water bombs--along with its bazookas and launchers--provide a very literal example.
 * Explosive weapons in X-COM games work this way, though damage from the most powerful bombs just cut off at a certain (quite large) distance rather than continuing to fade. Aside from hitting friendly units, a misplaced grenade may also destroy valuable loot or stunned prisoners or trigger Exploding Barrels.
 * A necessity in Prototype where, short of the most powerful ground vehicle in the game, you are your most reliable source of splash damage once the game starts throwing AT YOU waves of Mooks, Elite Mooks, as well as the beyond-elite mooks that will make you call out the Spiteful AI!
 * Age Of Empires I has catapults and juggernauts, while the sequel introduce mangonels, onagers, bombard cannons and cannon galleons. However said Splash Damage is very dangerous as it can damage your own soldiers en masse.
 * The Tribes series, being a game where players are zipping across the map on Jet Packs at 400kph, relies primarily on explosive weapons to deal damage. The famous Spinfusor - a weapon that shoots what are essentially exploding blue frisbees, is the staple bread-and-butter weapon that almost all players carry with them. Regular 'ol projectile based guns are sidelined, and used mostly just for killing flying players.