Game feel and juice
Same hit, two feelings
Picture this in Hyper Shards. Your laser hits an alien ship, and it just disappears. No sound, no flash. It works, but it feels flat.
Now picture it again. The ship flashes white, bursts into sparks, the screen gives a tiny shake and a crunchy boom plays. Same rules, same score, but this one feels amazing.
The second version has juice: extra feedback that gives an action a big reaction.
Game feel and juice
Game feel is how a game feels in your hands: does it react straight away, and is every action satisfying? Designer Steve Swink wrote a whole book about it, Game Feel, in 2008.
In 2012, two indie developers gave a famous talk called Juice it or lose it. They took a plain block-breaking game and added effects one by one, without changing a single rule. By the end it felt like a different game. Juice changes how a moment looks, sounds and feels, never the rules.
Bolt says: In the studio's colour language, green means the fun players feel. Juice is pure green.
Quick check
Juice changes the rules, for example by giving aliens less health so they pop faster.
- True
- False
Show the answer
False
Juice never touches the rules. The alien has exactly the same health. Juice only changes how the hit looks, sounds and feels.
The juice toolbox, part 1
- Screen shakeThe whole view wobbles for a moment, so a big explosion feels heavy and powerful.
- ParticlesLots of tiny sparks or leaves that fly out and fade. Each one is a small object with a position, a speed and a lifetime, often under a second.
- Hit flashAn enemy turns bright white for a frame or two when it's hit, so you know your shot landed.
The juice toolbox, part 2
- Hit stopThe game freezes for a few frames when a hit lands, often 3 to 6 frames, which is 50 to 100 milliseconds at 60 frames a second. Your brain reads it as a strong hit.
- Squash and stretchThings squash flat when they land and stretch when they move fast, like a bouncy ball. Disney animators made it a core rule back in the 1930s.
- Varied soundsA pop, a ding, a boom. Changing the pitch a little each time stops a sound getting repetitive.
Bolt says: Watch the badge stamp the next time you clear a stage in Superintelligent Game Studios. It squashes and stretches as it lands, the card gives a little shake, and sparks and a shine finish it off. That is juice.
How screen shake works
The game does not really shake your screen. It moves the camera, the window the game looks through, by a small random amount each frame. Then the shake fades away.
Many developers use a number called trauma, from 0 to 1. A big explosion adds trauma, and it drains away over about half a second. The shake size is trauma times trauma, so small hits barely wobble while big ones really rumble.
Bug hunt
1let trauma = 0; // 0 is calm, 1 is the most2function onBoom() {3 trauma = Math.min(1, trauma + 0.5);4}5function update(dt) { // dt: seconds since last frame6 const shake = trauma * trauma;7 camera.x = (Math.random() * 2 - 1) * 20 * shake;8 camera.y = (Math.random() * 2 - 1) * 20 * shake;9 trauma = Math.max(0, trauma + 2 * dt);10}
After the first explosion, the screen shakes forever and never calms down. Which line is the bug?
- Line 3
- Line 6
- Line 7
- Line 9
Show the answer
Line 9
Line 9 adds to trauma every frame instead of draining it. It should be trauma - 2 * dt, so a full shake of 1 fades to 0 in half a second.
Too much juice is noise
Juice is like salt on food. A little makes it great. Too much ruins it.
If the screen shakes on every single shot, players can't see the enemy bullets, and some people get motion sick. If everything sparkles, nothing feels special.
A good rule: the biggest effects for the biggest moments. A boss exploding gets the big shake. A normal shot gets a tiny flash.
Bolt says: Many games add a setting to turn screen shake down or off. It is a small option that makes the game playable for more people.
Juice pick
Idea: every laser shot in Hyper Shards gets a big screen shake and a huge boom. More juice means more fun, right?
What is the best reply to Remy?
- Yes, add the big shake and boom to every shot
- Keep a tiny flash for normal shots, and save the big shake for big moments like a boss exploding
- Skip juice completely, because effects only slow the game down
Show the answer
Keep a tiny flash for normal shots, and save the big shake for big moments like a boss exploding
The biggest effects belong to the biggest moments. A big shake on every shot hides enemy bullets and makes the boss explosion feel ordinary. No juice at all makes the game feel flat.
Juice needs good controls
Sparks and booms make a game feel exciting. But if the ship reacts late when you press a button, no amount of juice can fix it.
Juice is the icing. Good controls are the cake. A great game needs both.
Bolt says: Next lesson: shaders and visual effects, the tiny GPU programs behind glows and flashes.
Fact-checked 9 October 2026
- Game Feel by Steve Swink (Elsevier) shop.elsevier.com
- Game Developer: Is your game juicy enough? (Juice it or lose it) gamedeveloper.com
- Game Developer: Juicing your cameras with math (Squirrel Eiserloh, GDC 2016) gamedeveloper.com