based on Street Racing
written by Mark Overmars using Game Maker 6
images by Martin Bérubé and Sander Steenhuis
ported to Android by Adam Hlaváček
Published under GNU GPL 2
Source code is available at https://github.com/PheasantsTech/KeepLeftAndroid
Original PC version is available at http://www.rupert.id.au/tutorials/gamemaker/examples.php