Any good browser should work, I've not tested it in much though (Chrome on Ubuntu).

Theoretically it would work on iPad if I added touch controls, that may yet happen in the future. Controls are purely by dragging the mouse now.

Total time developing: 16 hours (including about 10 of those on the libraries themselves which are on Github for public use and my own use during the weekend).

Library :: http://github.com/robashton/layers

and

Game :: http://github.com/robashton/planethinking

I know what you're thinking, and yes - I am the greatest living artist of all time.