Fireboy & Watergirl 7: and Friends

Fireboy & Watergirl 7: and Friends is the two-player temple puzzle the series is built on, with three extra hands. Fireboy walks through lava and dies in water, Watergirl is the other way round, and the three friends - one key each - reach the switches, lifts and buttons a pair alone cannot.

Thirty-six levels of machinery: a lever held on one side of the room is a door on the other, and most of the thinking is deciding who stands where and when. Every diamond counts towards a perfect score, and each level also has a time to beat, so a careful run and a fast run are two different games.

Playing it well

• Split the room. Send one character to the far lever and keep the other on the near platform - the level is a machine, and the two of you are its operators.
• Green pools are safe for both. The green liquid is neutral ground; lava and water are not, and each of them kills exactly one of you.
• Mind the timing. Platforms move on their own schedule - watch one cycle before you commit to it.
• Collect as you go. A diamond left behind is a level you have to replay, and the perfect score needs all of them.

It is an adventure game for one or two players on a shared keyboard, and it runs in the browser with nothing to install.