Colony

How to play

• Grow. Your cells eat the food in the blue glass and divide into the next tile. Click the board to steer growth toward a spot.
• Reach quorum. Every cell releases a signal. Where cells are packed, it builds up until the tiles switch on and glow gold.
• Spend charge. Tiles in quorum fill your charge. Spend it on Swarm, which sends cells flying to a far spot, Biofilm, which shields a glowing patch, and Toxin, which kills cheaters, rivals and immune cells near a glowing patch.
• Mutate. Every star you win buys mutations in three branches: growth, signal and teamwork. Take up to three into each level.
• Take the challenge. Every level has one challenge that asks you to win it a harder way. A level you met it on carries a gold gem.
• Score. Each star is worth 1,000 points and each challenge 500. A faster win adds up to 1,000 more. Save your total under your initials on the score board.

The science in each level

Petri dish. Bacteria release small signal molecules all the time. Only when enough cells are close together does the signal pass a threshold, and then they change their behaviour all at once. This is quorum sensing.

Flow cell. Moving water carries signal away as fast as it is made. In streams, pipes and our own bodies, quorum sensing switches on in sheltered places such as crevices and pores.

Antibiotic. In quorum, many bacteria build a biofilm: a shared matrix of sugars, proteins and DNA that protects the cells inside, including from antibiotics. Our lab studies lactonases that break down the signal, so that bacteria never reach quorum and never build that shield.

The quencher. Lactonases cut quorum signals apart. Bacteria, plants and animals make them, and our lab engineers them. In Quench you play the enzyme.

Cheaters. Cells that stop making signal still enjoy what the colony shares, so they spread, until too few cells are left doing the work and everyone loses. Pseudomonas aeruginosa polices them with cyanide made under quorum control, which only cooperators resist.

Phage. Viruses of bacteria spread fastest through crowds, and many bacteria raise their defences once they reach quorum. In the game this is all or nothing: phages burn through green cells and cannot infect gold ones.

The host and the rival. In quorum, bacteria can kill the white blood cells sent to clear them, and arm themselves against other species with toxins and molecular needles.

Colony is a teaching game. Its rules are simplified and its rates are made up.