In LineRider, you get to build a course for your little sledding man to journey around you're own blank slate. You can do whatever you like with your line rider as long as the path you've built allows gravity to have an effect on him. Or you can simply launch him into a white oblivion for your amusement.
You can really go nuts with making the landscape and whatnot. There are three different colors you can use for the lines and if you disconnect the magnet feature which automatically connects the lines then you can even draw background for your level. You can draw free-form or use straight lines with the line tool. Best of all you can erase just one specific color line at a time.
If you've created a long level and you don't want to keep playing through the whole thing to test out your new areas, you can always flag your progress and return to that point. Once you've perfected your course you can save it locally or even upload it to linerider.com and share it with all the other level makers out there.
When you first get this app, register for linerider.com and download some of the already submitted tracks. They will blow your mind. Use these as inspiration and guidance for the different levels that you will eventually create as you dig deeper and become more skilled at utilizing all the tools, momentum, and angles that this game has to offer. It's definitely not for everyone, but anyone who can draw a line and likes watching their finished product will enjoy LineRider.