Lay a loop of little wooden track, set an engine down, and watch it chuff contentedly around your world.
Build a track and let a tiny engine ride it. Drag to lay wooden rails, connect them into loops, then spawn an engine that chuffs along your layout. Click junctions to flip them and send the train a different way as a slow day-night wash drifts over the scene.
Chuff is original, and its ancestor sits on a great many living-room floors: the wooden toy train set, where track is assembled by hand into whatever loop the pieces allow.
It keeps that scale deliberately. Serious model railways are about fidelity — timetables, scale ratios, weathering — while the wooden set is about laying track and watching something go round, and this follows the wooden set.
The junctions are the one place it asks for a decision. Flipping them redirects the engine, so a layout can be built to send the train somewhere different each circuit, which is as close as the toy tradition gets to a puzzle without abandoning the watching.
Chuff is an original relaxing model-railway toy in the calm sandbox genre, a free browser game with no fail states, just track to lay and a train to watch.