Reaction Animations


Reaction Animations -- It's probably safe to say that how an enemy responds to being hit is equally as important to making an attack feel satisfying as the attack itself. Reaction animations are also, sadly, one of the more overlooked features in games. Agnostic of genre, reaction animations are also important not just for feel but also serve a very functional purpose, that when lacking, can severely impact the quality of a combat system.

Fighting Game Inspiration

At least for the titles I've worked on, and from what I can gather referencing and researching other action titles, a lot of hit reactions are inspired by old school fighting games. Because stun time is such an important characteristic to how fighting games played, it's been essential for the genre to refine and polish hit reactions.

As far back as Street Fighter II for example, you can see a breakdown of several types of hit reactions that still remain present in modern action games.

Hit Reaction Types

The most important thing to consider when creating hit reactions is how they are broken down by type and category - essentially asking, what is their purpose?

But, there are a couple of additional attributes to consider:

• Direction: Most games employ a technique of snapping the character's facing to match the hit location on impact. This ensures that the animations line up properly. Additionally, unless you're doing some tricky impulse correction (for camera reasons?! ) you want to make sure if there's translation -- it goes in the correct direction as well.

• Impact Location: Depending on the type of attack, it may also be desirable to differ the reaction based on where the impact has occurred. This is, for obvious reasons, much more important for projectile based games than it is for action games. 

• Character State: It's also extremely important, especially depending on your system set up, to vary hit reactions based on the character's state. Is he lying flat on the ground? Is he flat against a wall? Floating in mid air? Depending on the amount of states your system supports, this can also severely bloat your animation count.

But when you do get to breaking them down, it's really important to consider two things:

1. Do you have enough variety and function to support all of your player attacks properly?
2. Do you have enough variety to create functional differences that support gameplay, IE, differing states and frame counts.

Usually, a common list might look something like this:

• Standard/Normal Hits
• Low frame count (10-25) most common reaction.
• Minimal baked in translation supports variety with programmatic impulses
• Usually demands the largest amount of visual variety due to the frequency of use; you may also want to support hit direction here. (right to left, up, etc.)

• Stagger/Stumble
• These should be more pronounced than basic hits, with double or even triple the frame count.
• Good for communicating a distinct difference between basic attacks and stronger attacks.

• Flyback
• A powerful reaction that sends an enemy flying away from the player.
• This serves a few purposes: 
• It actually helps the enemy by creating distance between the player an the enemy, forcing the player to change their tactic or allowing the enemy a chance to recovery.
• It creates a powerful reaction to make the end of a combo or a powerful attack feel distinct from other attacks

• Launch/Lift
• This is usually dependent on whether or not your combat system includes some type of air juggle system.
• In this case, you want to bake in the vertical translation to a very specific point that allows the player maximum opportunity to combo the enemy mid air.
• It can also be used, or small variances of it, can be used for large explosive reactions.
• This system is going to require creating a group of air based hit reactions, specifically an air version of normal hits, and maybe even stagger hits.

• Crumple or Stun Loop
• This an extremely long hit reaction, possibly one that supports an indefinite period of stun for the enemy, that can be used in a couple of ways.
• It can be used to support a stun system that may open up contextual opportunities for synchronized kills.
• It can be used as a form of crowd control, taking enemies out of play for an extended period.

• Knockdown
• This is a reaction that if authored correctly, can be used both in the air and on the ground.
• It's purposes is to instantly floor the enemy at the feet of the player, allowing for the opportunity of juggling the enemy on the ground.
• This generally requires ground/flat based hit reactions, otherwise you run into situations of having to awkwardly handle basic reactions while still in this state.

Here's a clip (masterpiece?!) that shows most of the above hit reactions used in a long string. You can see how the combo flows better and how stronger attacks distinguish themselves.

The above list offers a wide variety of differing hit reactions that support a pretty complex combat system. It also creates a functional difference between hit reactions -- as each reaction serves a specific purpose that rarely coincides with another reaction.

Satisfying Hit Reactions

The last thing to consider is that creating a satisfying hit reaction still requires authoring them correctly. There are still a few things to consider.

• Minimal/Zero tween time: You want to ensure that hit reactions feel snappy. One common mistake is to use a standard blend time rather than instantly popping into the animation. If you use a standard blend time of anywhere from 3-6 frames, it will cause the hit reaction to feel sluggish and soft.

• Extreme Posing: Another common mistake is not creating an extreme enough pose on the first frame. Especially considering that enemies may be in a variety of attack poses, from mid-strafe, to mid-attack, if the hit reaction does not appear extremely different than the initial pose, it will also feel soft or weak.

• Baking in Translation: It's important to do this carefully, but authoring translation can make hit reactions feel more powerful. For example: a stumble that bakes in a couple meters of translation will feel a lot stronger than one authored in place that relies on programmatic impulses.

Overall, while most games have reactions, it is not as common for games to consider the reaction system as important or significant to gameplay as high quality action games such as Devil May Cry, Bayonetta, and God of War. Often times there is a lot more complexity and variety that goes on in a hit reaction system for modern day action games. Creating distinct animations for various power up modes, special attacks, etc. But, even at a basic level, it's also something that can benefit games of all genres, whether you're a third person shooter, 2d side scroller, or first person shooter.