Travel 100 metres without being seen.
Put on a performance for a CCTV controller. You could improvise a short play, show off a dance routine or hold a full blown talent show.
Go guerrilla and change a place with plants.
Become a citizen of the new nation of Nowhereisland: a Nowhereian.
Go for a walk; bring back your favourite memory and then recreate it.
Become a Champion Worm Charmer!
Collect 26 photos of the letters A-Z in different places.
On this trail, when you cycle at your normal speed you're travelling at about ten times the speed of light. Can you travel ten times slower than you normally would without falling off your...
You are currently at the Sun, over 3.5 billion miles away from the edge of our solar system. Cycle there and create an astronaut report detailing your successful mission.
You are currently on Pluto, over 3.5 billion miles away from the Sun. Cycle there!
You're at Mercury, a planet that can reach temperatures as high as 465°C and as low as -184°C. Design a creature that could survive on this planet.
Carry out a dog survey in two different parks.
Paint a stone red. Leave it somewhere and then come back at a later date to see if you can find it again.
Plant some beautiful flowers or start a community garden to make a neglected place more beautiful.
Explore your local area looking for signs and words that command you to do things. If you find one, do what it says.