Genre: interactive fiction scavenger hunt
Format: mobile browsergame (made with Twine)
The game used to be playable via save-theworld.nl but is now archived via the link below:

About the game:
A mysterious voice asks you to help him. The world needs saving from aliens. You will need to go, now! Bring some chalk, paperclips and a bit of rope, and enter the city for a scavenger hunt turned upside-down.

What I did:
This is an original solo-project. Save the World was originally designed for the Playful Arts Festival in Den Bosch in 2015. After this first version, new editions were commissioned by several festivals and cities: W00t in Kopenhagen, Play Happens in Genova, Adventure X in London, the Architecture weekend in Utrecht and the council of Lelystad.

Event Design:
This is one of the first projects I designed specifically for the public space. The idea came from things like guerilla-gardening and guerilla-knitting; ways for people to beautify their own surroundings and make a small impact. ‘Save The World!’ plays with the idea of purpose; if you gamify the public space, are you able to make people look at their surroundings a bit better than usual, and are they willing to make small changes to it? By asking players to add to each other’s small artworks, the idea of a small public communal ‘museum’ starts to take shape, and even when the chalk is washed away by the rain, players will remember their contribution when passing the same spots again.
The article below on Indietoaster makes more clear how the whole project works and also provides some photos from the route.

Reviews and articles:
Indietoaster (interview plus photos)
Adventuregamers.com (review)