How the Sand Avalanches and Pearl Rolling Work

Sandfall - abelian sandpile criticality and avalanche granular physics schematic
Fig 1. Granular avalanche mechanics diagram: discrete sand cell grid, toppling threshold cascade, immovable rock barriers, and gravitational pearl transit corridor.

In Sandfall, you sculpt terrain using pure sandpile physics. You don't build rigid stone ramps; you pour loose sand grains that stack and tumble naturally.

The game models the classic avalanche tipping point. Each grid cell can hold up to 3 grains stably. The instant a cell receives a 4th grain, it topples, spilling one grain to each of its four neighbors (up, down, left, and right). If neighboring cells are already full, they topple too, setting off cascading sand avalanches across the board.

Your goal is to guide a dense, heavy pearl from its starting ledge into the green goal basin. The pearl responds to gravity and rolls downhill along sand slopes. If the terrain is flat, the pearl stops. If you build smooth downward dunes, the pearl gathers speed and cruises across rock chasms.

Pouring Controls and Grain Budget

Sculpt sand dunes and release the rolling pearl using straightforward mouse and keyboard controls:

Key / Click Action What Happens
Left Click & Hold Pour Sand Grains Streams sand from your cursor into the grid column, triggering avalanches when cells topple.
Spacebar Release Pearl Drops the pearl from its starting mount onto your sculpted sand dunes.
Right Click / Z Undo Pour Steps backward through your recent pours and refunds grains to your budget meter.
R Reset Puzzle Clears all poured sand and resets the pearl back to its starting perch.

How to Beat Level 4 (Avoiding the Wide Pit Stall)

Level 4 features a wide gap between two immovable rock ridges. Beginners try to dump all their sand into the middle of the pit, hoping to fill it up like a sandbox.

Here is why that fails and how to clear it easily:

  • The Avalanche Pit: Pouring directly into a deep pit causes sand to spill sideways into useless corners. You run out of your grain budget before the ramp reaches the far ledge.
  • The Anchor Trick: Immovable rock blocks act as natural retaining walls. Pour your sand directly against the left face of the rock pillar. The rocks trap the spilling grains, letting you build a steep ramp using half the sand.
  • Stepped Descents: Build a gentle two-step incline that slopes downward from the start point directly to the goal basin. Release the pearl, and its momentum will carry it across effortlessly.

Tips and Strategies for Harder Levels

Later stages challenge your spatial planning and grain efficiency:

  • Level 7 (Chamber Pouring): Sand must be poured through narrow ceiling slits. Pour in short taps to observe where avalanches spread before committing all your grains.
  • Level 10 (Climbing the High Wall): To carry the pearl over a tall stone wall, build a wide pyramid base first. A wide base allows the peak to rise high enough without constantly collapsing sideways.
  • Level 12 (The Gauntlet): Multiple pits and staggered ledges. Build small connecting bridges between rock teeth rather than trying to fill whole chasms.

Grain Budgeting and Par Scoring

Mastering late-game levels requires strict grain economy to earn top star ratings:

  • Preserve Unpoured Grains: Unused sand remaining in your budget meter at the end of the puzzle converts into bonus score. Keep ramps compact and narrow.
  • Tap Pouring vs Holding: Holding the mouse pours sand in a continuous stream. For delicate peaks, click in short taps to drop individual clusters, allowing avalanches to settle before adding more weight.
  • Test Rolls with Undo: You can release the pearl to test your slope, and if it stops short, tap Z or right-click to rewind your recent pours, refine the ramp angle, and try again.

Frequently Asked Questions

Sand piles can only hold up to 3 grains before toppling. Adding a 4th grain triggers an avalanche that spills grains in all four directions, flattening sharp peaks into wide gentle dunes.

The pearl is dense and rolls naturally downhill along sand height gradients. Build smooth, connected downward slopes to carry the pearl past chasms and into the goal basin.

Right-click or press Z to undo your recent sand pours step-by-step and refund your grain budget. Press R to reset the entire level if you need a fresh start.

Built with pure vanilla HTML5 canvas and standard Web Audio (no external engines or heavy libraries).