It needs WebGL 2. Try a recent Chrome, Edge, Firefox or Safari, and make sure hardware acceleration is on.
The code is the whole build in one line of text. Send it to a friend, then they paste it here.
Scale: 1 stud = 8 mm, 1 brick = 9.6 mm high, a 2×4 brick weighs about 2.5 g (model values for a generic ABS toy brick; the page is independent and not affiliated with any toy or film brand).
The centre of mass of the stack above a joint must stay over its support. For a free stack of N bricks, each shifted by DN = (L/2)·HN (harmonic series), the overhang can grow without limit but slowly: 10 bricks of L = 31.8 mm reach 46.6 mm.
Drag on the silhouette: F = ½ ρ Cd A v² with ρ = 1.225 kg/m³, Cd = 1.2. Every horizontal joint is tested for tipping, F·hcp + Σ m·a·h against W·lever + nedge·fstud·b, and for sliding, Fh against μW + n·fshear. A free 2×4 tower of 20 bricks tips at about 3 m/s; clipped together it holds about 17 m/s.
A table accelerating sideways by a adds an inertial force m·a at each brick's centre. A free 3-brick stack tips at a = g·b/H = 5.38 m/s².
Load is passed down the contacts, split in proportion to the contact area. The bottom of a 40-brick column carries about 9 kPa while ABS is about 40 MPa strong, so bricks never crush: towers tip or come unclipped. The colour is relative (most loaded brick = red).
Stud holding force (about 2 N, typical 1 to 3 N) and friction (μ 0.30 dry) are model values and depend on tolerances. Not modelled: plastic bending, impacts, a collapse in motion, diagonal wind. Challenge stars use these same statics, so they tell you which builds would stand, not how they fall.
Each line compares the kit's algorithm with a separate textbook value or a separate re-implementation (own constants).