I have added a night time mode and fixed the glitch when switching images. The preloader is now showing an image.
July 10
I have added support for larger maps. The first example used a 1280x1280 map. This example uses a map that is 3200x800 pixels. It consists of 7 800x800 images of the original 3200x800 image. First image covers pixels 0-800, second 400-1200 and so on. There's a slight pause when the images are switched, I haven't figured out a way to get rid of this yet. I've also added short commands for some of the settings.
June 27
I have added a parallax effect to the sky. Slows down the engine a bit, but it adds some depth. I've also added mipmapping to decrease aliasing near the horizon. Doesn't make a huge difference, but it does not slow down the engine.
June 26
It seems this is going towards a motorcycle game. Added two jumps on the road. Right now they are only marked as darker areas, but it would not be too difficult to make them real objects with a height. You cannot turn in the air, only lean. Note that the jump physics is very temporary.