What properties make moves "unblockable?"

[BigOlePappy]

Like, Evil Ryu’s and C.Vipers look like just a normal jumping kick.

[Trouble_Brewing]

They’re not properties of the moves, but a glitch in the game engine.

[Komatik]

And more to the point, many unblockables in different games are not truly unblockable, just really hard to block. SF4 unblockables and the simultaneous high-low strikes Guilty Gear’s Eddie is famous for can both be blocked - in SF4 you have to move the stick from neutral to the proper direction on the exact frame the attack would hit you (holding a direction doesn’t work). In GG, you have to block whichever of Eddie’s attacks is a considered a projectile first and block the other one the very next frame. Both are possible, just really hard.

Some attacks have just been designated as unblockable though, but they’re explicitly designed to not cause problems. The Eddie ones are intentional, but the SF4 ones are indeed a result of a glitches in the game (It’s at least two separate ones).

[Zio_Name]

As Komatik said, i don’t really know the exact frame for every unblockable, though i know (taled about it with an Ibuki Main) that her kunai, for being unblockable has to hit on the 37° frame. And there is still also the situation of total randomness where an attac can hit both in the front or as a cross-up, also some sort of “frame-perfect”, input. Most people don’t know about this and often consider something that may simply be a fake cross-up as an unblockable.

[ilitirit]

In SSFIV it’s a combination of things usually having to do with proximity blocking, hit/hurtboxes, pushboxes and that wakeup always ends in a standing frame if you’re not holding away from an attack. Look at the hitbox images in this post and the explanations. Not every unblockable happens like this, but this should give you a better idea.

DWU or Unblockables?

I still don’t understand this. I don’t know why they would need to add another frame of hit-detection as the game can check for collision and which direction you’re holding in a single frame. Unless they’re doing something really weird, the game will do this on every iteration of the game loop (check which hit-boxes are colliding; check if the direction the player is holding a valid block input). It also doesn’t explain why that would remove most of the unblockables because most of them don’…

[BigOlePappy]

In SSFIV it’s a combination of things usually having to do with proximity blocking, hit/hurtboxes, pushboxes and that wakeup always ends in a standing frame if you’re not holding away from an attack. Look at the hitbox images in this post and the explanations. Not every unblockable happens like this, but this should give you a better idea.

DWU or Unblockables?

Thanks, that post gave me a much better idea. So basically the engine cannot block forward and backwards at once in some scenarios?

[ilitirit]

Thanks, that post gave me a much better idea. So basically the engine cannot block forward and backwards at once in some scenarios?

In short, some jumping attacks will hit in front. If you hold forward, you will get hit. So in order to block them you have to hold backward. But the mere act of holding backward changes your hitboxes in ways that causes the jumping attack to hit at the back instead (or vice versa). It’s a Catch 22 situation.

[Komatik]

Also explains why it can be solved by just frame blocking - that way the attack has a direction it hits and your collision boxes don’t get altered beforehand. Same with the qcf/qcb technique for blocking those setups. Stay low, no collisions, rise up, first tall frame is already definitely on one side or another and you’re holding the proper block.