Tap an empty cell to drop the part you have selected. Tapping the same cell again flips a mirror between its two diagonals, and a third tap takes it back into stock. Nothing is spent until you leave it there, so experimenting costs nothing.

Splitters arrive at stage ten and prisms at stage eighteen. Both show up on a stage built to need them — a splitter stage has two receivers that cannot be reached one after the other, and a prism stage has receivers that only accept red or blue.

A wall simply stops the beam. An absorber also stops it but is placed where a promising line would otherwise continue, so it exists to kill the obvious answer. Neither can be moved or removed.

They move it to their twin while keeping its heading, so a beam entering a portal travelling right leaves the other portal still travelling right. That breaks the straight-line geometry your eye expects, which is exactly the point.

Yes. Beamwork is completely free in your browser on ArcadeWhale. There is no purchase and no sign-up — open the page and start placing mirrors.

No. It runs directly in your web browser and works in Chrome, Safari, Firefox and Edge on desktop, tablets and phones. There is nothing to install.

Every stage gives you one more part than the shortest solution needs. Three stars means solving it without spending that spare, which usually means finding a route that uses a fixed mirror or a portal the room already provides.

No. Every stage was checked by an exhaustive search over all legal placements before it shipped, and any that could not be solved was rebuilt. If a stage is beating you it is hard, not broken.

Thirty-two. The first nine teach mirrors against walls and absorbers, the middle group adds splitters, portals and colour filters, and the last group adds prisms and combines everything.

Yes. Your stars on every stage and your coins are stored on your device, so closing the tab does not reset you. You return to the first stage you have not finished.