Sim

Rules — Sim

• The board is a complete graph: every dot joined to every other dot. All the edges start out gray.
• Each player owns a colour: player 1 navy, player 2 maroon.
• On your turn you paint any still-gray edge in your colour. No edge is ever forbidden.
• You lose the moment you close a triangle in your own colour — three edges of your colour joining three dots pairwise.
• Only triangles whose three corners are dots of the graph count. Two edges merely crossing in the middle of the drawing are not a triangle.

You don't have to hit an edge exactly: press near it and the edge you are about to paint is shown semi-transparent. Slide to correct it if it isn't the one you meant, and release to paint.

Levels:

• Basic — K₅, 5 dots and 10 edges. The only level where the whole board can be filled with nobody closing a triangle.
• Medium — K₆, 6 dots and 15 edges: the classic Sim. It can never end in a draw.
• Hard — K₇, 7 dots and 21 edges, much more room. No draws here either: K₇ contains K₆.

Navy already owns A–B and B–C. The cursor presses below the bottom edge, not exactly on it — close enough is enough: the edge about to be painted lights up semi-transparent first, so you can check it before releasing.

Releasing paints A–C navy… and that closes the navy triangle A-B-C. Navy loses right there. That is the whole game: you must keep painting without ever being the one who completes a triangle of your own colour.

Careful with the third edge of a triangle you didn't see coming — on K₆ every edge belongs to 4 different triangles at once.