Today I want to make a distinction between hitstun and pseudostun in singleplayer games. Idk if this distinction has been made but it needs to be.
Pure hitstun is a mechanic where, once hit, an enemy will play the flinching animation and go into a unique state that they will be trapped in until their hitstun timer runs out. Being a unique, discrete state gives hitstun some unique properties - it interrupts any move or action the enemy's doing, it freezes them in place, and it resets their logic (attack timers, decisions, etc.) to something like neutral.
Outside of some 2D beat 'em ups, pure hitstun is actually not that common - usually games mix it up by letting enemies do things like dodge out of their stun state, or block, or something. One such "hack" games use is super armored attacks which can activate out of hitstun. This leads into what I will call pseudostun.
Pseudostun looks and sometimes even acts a bit like hitstun, but it's not hitstun. It's when enemies can activate moves (& by extension continue their logic) during the hitstun state. And because moves usually have startup frames, this means that which ever move they activate will have to use super armor to work - otherwise the player's faster attack startup frames would let them win basically every time in the average modern game, one with slow well telegraphed attacks.
The reason pseudostun is used is usually simple - it's a balancing compromise. Balancing moves and enemy responses naturally is incredibly difficult & time consuming and even other hacky solutions (enemies dodging out of stun & countering) are very difficult to design in comparison. After all, not only does the dodge create disadvantage, but if the follow up attack has no super armor then players can probably move in and counter it before it has a chance to hit them. Or even outrange them. Pseudostun makes this simple - you make players feel like they're hitstunning enemies because it makes games feel better, and sometimes you even let players interrupt smaller less meaningful attacks. But as soon as attacks that matter come out, you can easily shut down the player's move properties and have them play by your rules.
Pseudostun has been around since the dawn of beat em ups in various forms. But I think now that we're in an era of Souls mechanics being used as a standard action game template, devs will have to increasingly start relying on pseudostun if they want more fast, CAG-y gameplay styles within that framework. Because Souls combat, and more precisely bosses, are just not very hospitable to generous, easily accessible hitstun. And while fighting game, cag and beat em up nerds will recognize the difference between proper hitstun and pseudostun, I believe regular players won't because they see hitstun as basically vfx, rather than a discrete and important mechanic.
