Recipe for the most improbable game ever: Draw a sledding hill with ramps, jumps, drops, and so on, then sit back and watch your rider careen down and around. That’s Line Rider in a nutshell, a game born in Flash, raised in a browser, and beloved by millions. If you’re one of them, or the concept sounds appealing to you, this is $2.99 very well spent.

Line Rider iRide recreates the original Web-based version to a tee, with the same set of drawing tools, the same physics engine, and, of course, the same scarf-wearing little sledding dude (who goes by the name Bosh, if that matters). You start with a blank canvas and your finger, which acts as a pencil. You can draw a regular line, an “acceleration” line (which makes Bosh go faster regardless of incline), and a scenery line that Bosh will pass right through. There’s also a straight-line tool and an eraser.

And that’s it. Now you let your imagination loose. You can tap the Play button at any time to see how Bosh fares on your newly developing track. Users with short attention spans, take note: It takes considerable patience to craft a “ride” that doesn’t quickly end with your little rider plummeting to his demise. Some players will get bored or frustrated (your fingertip makes for a less-than-precise pencil) inside of three minutes, while others will find hours’ worth of entertainment.

For those in the latter category, Line Rider lets you save and share tracks online and download and rate other users’ tracks. (Downloading tracks is a great way to see what skilled designers can accomplish with Line Rider.)

Although other mobile versions of the game have a few extra features, like reverse-acceleration lines, more kinds of scenery, and a curve-smoothing tool, Line Rider iRide features the cool Night Ride mode and the Gravity Tilt option: Bosh responds to the iPhone accelerometer.

Not sure if this is your cup of virtual sledding? You can still play the original Line Rider online—the perfect way to try before you buy.