Thoughts about experience.

Most people know what “experience” means in the context of games, but defining a commonly-used term forces me to think about it concretely and precisely when I usually take it for granted, so I’m going to do it!

What is experience?

Lots of games have characters that grow over the course of the game, becoming more powerful and learning new abilities.  This ability to grow is usually represented by a currency called “experience.”  I’m going to abbreviate “experience” as EXP,  to indicate that it is a term with special meaning distinct from the usual meaning of the word.  EXP is gained by performing certain activities.  In some games, EXP is spent to purchase upgrades.  In others, reaching certain milestones of total EXP unlocks upgrades.

Why is EXP important?

Gaining EXP is a strong incentive. Players tend to perform activities that reward EXP over activities that don’t.  By changing which activities award EXP, and how much, game designers can influence their players’ behavior to suit the designers’ goals.

Common ways to gain EXP

Most of these examples are from video game shooters with “RPG elements”, RPG video games, and table top video games.

Individual EXP for killing enemies: In games where most situations are combat challenges, this method is obvious. The goal is to kill enemies, so reward the player who kills an enemy. This works well for single player games, but in multiplayer games, giving all the EXP to the player who lands the killing blow does not account for teamwork. If player A deals 90 damage to an enemy and Player B deals only the last 10 damage that kills it, player B will get the EXP and player A will feel cheated.

Individual EXP for assists: This is the obvious fix to the previous method.  Everyone who participates in killing an enemy gets some EXP. There are various ways to do this.

  • Full EXP for the killing blow and half EXP for anyone else who damaged the enemy.
  • Award EXP proportional to damage done.
  • Using a helpful ability on a player engaged with an enemy awards assist EXP when that enemy is killed.
  • Award assist EXP for using non-damaging abilities on an enemy, like knocking it down, pushing it out of position, and so on.

Making an attempt at fairness reveals how difficult it is to precisely define fairness.

EXP for completing objectives: This is mainly used in video game that have other things to do besides killing enemies.  Usually, most of the systems are about killing enemies, with some longer-term objectives on top, like “Control an area”, “Escort an object”, or “Capture a flag”. Accomplishing these objectives is another source of EXP, alongside killing enemies.  Some objectives (e.g. hold an area) award EXP equally to everyone involved. Others (e.g. capture the flag) award EXP to the player who accomplishes it, and maybe also to players who assisted that player.

Group EXP for overcoming obstacles:  This is common is video games and tabletop games where players form teams or parties.  Any accomplishment by the party awards equal EXP to all party members. Framing the achievement that grants EXP as “overcoming an obstacle” instead of “defeating an enemy” expands the types of situations that grant EXP: solving a mystery, navigating a hazardous area, convincing an NPC. It also handles solving a problem in multiple ways.  Players can get past a checkpoint by sneaking, fast-talking, or fighting, and get the same reward.  If combat is dangerous or expensive, players are encouraged to try non-violent solutions.

Group milestone leveling: This is used in tabletop games that emphasize story, Instead gaining EXP for every obstacle along the way, every player gaining a large amount of EXP for reaching a significant narrative milestone, like defeating a boss, or wrapping up a story arc.  This lets the GM choose how powerful the party will be at any point in the story, and less accounting is required of both players and GM.

EXP per skill: This is a paradigm shift that rewards players for their actions instead of for the effects those actions have.  Instead of one pool of EXP, characters have multiple pools, linked to skills or groups of skills.  For example, a character may have a “shooting” skill, and could gain “shooting EXP” for attempting to shoot, or for shooting and succeeding, or for succeeding on difficult shots.  “Shooting EXP” can only be used to improve shooting-related parts of the character.  This method keeps track of a lot more than other methods, so it’s usually limited to video games, where the computer can do all the math.

Ideas for gaining EXP

In team games, it’s good for players to work together and help each other.  How do we know when a player has been helpful to another?  Humans intuitively use a lot of context to decide what certain actions mean, and that’s hard for computers to emulate.  A computer would like to say “Healing a teammate is good”, but healing a tank that’s at 3/4 health while a squishy teammate dies is a mistake.  Most simple rules for what is helpful and what is not can be gamed: players who are motivated to gain the most EXP can find actions that make no sense diagetically, like standing in a fire to let a teammate get unlimited EXP for healing.

One way to answer “does this action help?” is to ask “If this action did not happen, would things be worse?”  That’s easier for turn-based games or games with fewer verbs. Predicting the future gets more expensive the more complicated each situation gets, and how far ahead one has to look.  Here’s a simple example.  In Pathfinder, a Bard gives the Fighter +3 to attack, and the Fighter’s next attack beats the enemies AC by 1.  Without the Bard’s Inspiration, the Fighter would have missed, so the Bard definitely helps!  Grant EXP!  But what if the Monk trips that same enemy, knocking it prone and reducing its AC by 4. Does the Fighter hit because of the Bard or because of the Monk?  Even in this turn-based example with chunky numbers, it’s hard to assign causes to results.

Another concern in team games is fairness. EXP is a positive feedback loop. Characters that perform better get more EXP and more power, and then perform even better.  Small differences in effectiveness are magnified over time, and it’s hard to have a team of characters with vastly different amounts of power.  Limiting that difference in power can keep players from feeling frustrated. One solution is to award EXP to the group, not to individuals, but that may lead to the “free rider problem.”  Another solution is a limit to the difference in EXP between party members. A very effective character would stop earning EXP until other characters caught up.  The powers granted by EXP could also reduce this problem by weakening the positive feedback loop. If characters grow mostly horizontally (more utility options, diversification) instead of vertically (bugger numbers), that characters that are far behind can still contribute (in a few areas) just as well as a character that is far ahead.