Gravity Rush

Gravity Rush started with a deliberately awkward question: what would a physics puzzle look like if the player had to draw the puzzle, not just solve it? Most physics puzzles hand you a fixed toolbox; we wanted to see what happened when the toolbox was literally a pen. The first prototype had unlimited strokes, which was actively bad — players drew walls, boxed the ball in, and reached the goal in seconds.

The stroke budget fixed it. Limiting strokes per level forced real thought into every line, and it created the secondary game of finding more elegant solutions. Three-star runs almost always use fewer strokes than a bare-pass run, so the game quietly rewards reconsidering each line rather than just any line that works. Some players stop once they pass a level. Others come back a week later and find a much cleaner solution they could not see before.

Line physics sit on top of Three.js plus a small custom physics solver. Early builds had line collisions snapping to a pixel grid, which caused visible jitter on slow-moving balls. The current build interpolates collision surfaces across subframes, which costs a bit of CPU but eliminates the drift. Related intuitive-input physics work runs through Rope Snip — different inputs, same tension between an intuitive gesture and a precise simulation underneath.