Algodoo is a physics-based 2D sandbox developed and sold by Algoryx Simulation AB, and is the successor to the popular physics application Phun. Algodoo was released on 1 September 2009 after significant delays in production [. Algodoo is marketed as an educational tool and has much functionality with touch screen computers, computers with accelerometers, and the ]Intel Classmate PC. Algodoo's physics are based on the SPOOK linear constraint solver by Claude Lacoursière. In October 2011, Algoryx released two new programs: Algodoo for Education and Algodoo 2.0.0.
Simulations in Algodoo involves using the given tools (polygon creation, cut, brush, box, circle, gear, plane, chain, spring, fixate, hinge, tracer and laser pen) and features (CSG, Velocity modification, attraction, refraction, killer/immortal objects, cutter objects, water and scripting) to create scenes with high levels of intricacy. The simple interface of Algodoo allows a new user to enjoy themselves by creating simple cars and making their creations come to life with only a few clicks and drags, while still not limiting the creativity of those who want to make very complex machines, creatively achieving simulation objectives in a variety of ways.
Algodoo allows users to modify the gravitational force, restitution, friction, refractive index, density, layers of collision, controller acceleration, destruction and mirror keys, texture (allowing users to place a picture on an object) and color (and alpha channel) of a polygon, color and refractive index of water, fade distance, color and speed of light of a laser, color, speed, strength, impulse break limit, state, direction and controls of a hinge/motor, strength constant, damping factor and target length of a spring and fade time of a tracer, giving a lot of choices for users to change to get different results.
Although the GUI is essentially the same as in Phun, many significant changes have occurred in the scope of Algodoo's simulations. Two notable changes include a new optics modeling engine and a snap-to grid feature allowing for higher precision scene creation. The inclusion of optics has granted much more freedom in terms of using Algodoo's scripting language "Thyme", as one may now initiate events by hitting a geometry with a stream of laser light. Other notable changes include the inclusion of a velocities menu, allowing one to set a geometry's velocity to a set value, incompressible water, which allows for much more realistic fluid simulation, a plotting menu which allows one to compare and contrast different properties of a geometry, i.e. velocity at a certain time, position on the X and Y axis, velocity along the X and Y axis, etc., a new tab in the "options" menu that allows the user to visualize in real time many different forces that are affecting the objects in a scene,and many other new features, bug fixes, optimizations and improvements.
As it is based upon Phun, Algodoo still works upon a constructionist learning paradigm.
User Created Content
Sharing user created content among the Algodoo community is just as easy as it was in Phun with the usage of Algodoo's file sharing site, Algobox. There are currently over 30,000 unique creations stored, with that number increasing every day.
Originally, the upload system for Phun was a small site at the Academic Computer Club, Umeå University , it was then later moved to the Phunland site , in an "upload" sub-directory (which has since been deleted), the file sharing system was then moved to "Phunbox", a system which received 16874 uploads (the majority of which were .phn files (phun scene files), with the remainder .cfg files), a system made by Zuriki and Lukas Wolf (which was located at www.phunbox.net, which now redirects to the latest file sharing system), all scenes from Phunbox (now renamed to "Phunbox1") were next converted to .phz files (phun zip files) which was the scene format for Algodoo: Phun Edition beta 5.xx, these files contained thumbnails, textures used in the scene (user-made textures on objects), checksums and the .phn file (the scene), the new file sharing system was called "Phunbox2" (made by Lukas Wolf, which was located at www.phunland.com/phunbox/index.php (now redirects to the latest file sharing system)), unfortunately a lot of Phunbox1 scenes were "lost" in conversion, this new system (Phunbox2) received 12455 uploads (still stored) before being moved to algodoo.com/doobox (now a redirect of the latest file sharing system), a user suggested that Doobox may not be a good name for the file sharing system for Algodoo (Frank, from the Algodoo forums), Doobox was then renamed to Algobox (as suggested by Chronos, from the Algodoo forums), the address was then changed to www.algodoo.com/algobox , 2860+ files have been uploaded (and stored) since the site was moved to www.algodoo.com  (on September 1, 2009).