Bottle Cap Football: flick, clack, goal.

Bottle Cap Football is button football in the browser: flick your caps like a slingshot to knock the ball into the far goal. Play a friend on the same screen, a friend online on their own phone, or the computer on Easy, Medium, Hard or Legend.

It is the game the world plays as futebol de botão and fútbol chapas, live at capfooty.com.

Flicking caps is all physics, so a computer player that simply aims at the ball is either useless or a cheat.

And playing a friend online usually means accounts, servers and lobbies, which is a lot to ask for a quick game.

The Medium, Hard and Legend players simulate dozens to hundreds of possible flicks with the real physics before choosing one, so they never repeat a pattern, know the rules and avoid fouls. Legend also plays out your best reply to its top options.

Online, one player shares a five-character code and the two phones connect directly through PeerJS, with no accounts or server. Then come the touches that make it football: fouls, free kicks and penalties with a sliding keeper, yellow cards and a sin bin, and a broadcast-style 3D goal replay built with three.js.

It is live at capfooty.com with ten kit colours, four pitches from Old Trafford stripes to a fast felt table, synthesised kicks and whistles, and full-time stats for every match.

• 4

  computer difficulty levels

• 5

  characters to start an online match

• 4

  pitches to play on