Nature and effects
Learning paths through this topic
Make a tree or figure creep closer only while the player is not looking at it
The oldest scare in a dark wood is the thing that was further away a moment ago. It only works if the player can never catch it moving, and the cheap version is caught out by a quick turn of the head. Here is the rule that makes it fair and how to close the gaps in it.
Make bubbles rise and pop in a swamp, with a heavy belch now and then
Steady bubbles are pleasant. A swamp that is hiding something should breathe unevenly: long quiet stretches, a few lone bubbles, then a burst. The bubbles themselves should grow as they rise. Here is how to build it without keeping a list, so that skipping time or loading a save shows the same swamp.
Make ice crack and groan under weight and break only when the load is really too high
Crossing a frozen lake is a tense scene when the ice talks to you. It falls apart when the ice breaks at a random moment, or never does however thick the warning cracks get. Here is the simple rule for how much ice can carry, and how to turn the margin into creaks, cracks and a fair last chance.
Make the sea rise and fall on a real tide clock, so a cave floods on time
A story with a cave that can be walked only at low water needs a sea the player can read and plan around. A sine wave that repeats every day is wrong, since real tides slip later each day and swell and shrink over a fortnight. Here is a small set of numbers that feels right and answers when the way is shut.
Make a torch or candle flicker like fire instead of pulsing like a lamp
A light that brightens and dims on a sine wave looks like a breathing bulb, and one that jumps to a random brightness every frame looks like a fault. Real flames wander quickly with now and then a deeper dip. Here is a flicker that keeps the average brightness, can be set per torch and never goes dark by accident.
Fell a tree so it starts slowly, speeds up, hits the ground and settles
A tree that swings down at a steady speed like a door looks fake, and so does one that falls through the ground. A real tree starts with a slow tilt, then drops faster and faster, hits with a bounce and lies still. Here is the simple physics behind that, how long a tree of any height needs, and the trap at the start.
Grow a vine or root along a winding path at an even speed
In a puzzle where a plant grows toward a goal, the line should creep forward smoothly. Revealing one corner point per tick makes long stretches race and short ones crawl, and the tip can show a tiny flick at each bend. Here is how to draw exactly the right length at any moment.
Let vines grow along a wall as the dread rises, and never shrink back
Plants taking over a house is a slow horror that rewards the player's attention, but if the vines are tied straight to a meter they twitch when the meter wobbles and pull back when the scene calms down. Growth that you can see should only go one way. Here is how to tie it to the story and keep it moving at a believable pace.
Make rings spread on water where something falls in, and fade as they travel
Ripples are a small effect with a big feel, but a ring that is simply a growing circle does not look like water. The wave must travel outward, weaken with distance and time, wobble inside the ring and vanish after a while. Here is a formula that gives the height at any point, with many ripples at once.
Change the weather smoothly, so a storm always builds up through rain and can reverse
Switching between clear, rain and storm with a single fade leaves strange in-between looks, like heavy darkness without a drop of rain. If the player or the story changes the weather in the middle of a change, things often jump. Here is a way where every mix is sensible and any change can be turned around.
Let a forest fire spread tile by tile, with wind, at the same speed on any screen
A burning forest in a story must be readable: where it started, which way the wind pushes it, and how long until it reaches the cabin. Easy versions race along one row in a single frame, favour one direction by accident, or run faster on a fast computer. Here is how to make a fire that spreads fairly and repeats exactly.
Let wind sweep across a field of trees as moving gusts, not all swaying as one
Trees that all swing on the same sine wave look like a metronome. Random sway per tree looks like confusion. Real wind arrives as gusts that travel across the land. Here is how to make a wave of wind roll through, with some variety per tree and no visible repeating.