Stretch and Squash
This is Squash and Stretch, as you can see when you squash there arent really physics to it but on other hand, stretch does.
When applying Squash and Stretch always keep the same volume, for example if you stretch, the width becomes narrower and the length becomes longer.
Anticipation
If a character is about to run they almost fall back and then shoot forward or when a character jumps, they squat down and then shoot themselves up. Its all about the windup.
In my opinion i think anticipation is key in an animation and especially in video games because it gives time for the player to react. For example, if an AI is about to attack you, you can see it coming and dodge or block.
Anticipation is used in a lot of games like UFC or fighting games to Spider man PS4. In the video below you can see that when the opponent swings he pulls arm back or up etc. Its a quick transition but that is what makes people improve on their reaction times.
A. The start of the bounce – Height Decreases on each bounce.
B. Fastest Point/Stretch – Space between each bounce decreases
C. Squash on impact – Time gets shorter per bounce
D. Slowest Point/Normal Shape
Corey Aizlewood Games Designer 