No Limits is a coaster building "game", which allows the user to build and ride coasters. A demo can be downloaded at www.nolimitscoaster.de. The full version includes a complete editor, several sample tracks, and several types of coasters. The full version costs $25 USD. 

New: There is an update to NL that includes an importer for RCT tracks, so players can ride their RCT creations in No Limits. Due to differences in the physics of RCT/No Limits, the importing may not be perfect.

I have a few screenshots and a few basic tracks for download

An aerial view of a coaster

Another aerial view

Viper at SFMM

Another view of Viper

Clippy, that famous paperclip from Microsoft Office (who liked to help you write letters), is shown on this coaster car. Somebody must have set up him the bomb.

A "crashed" coaster, resulting from block brakes being too short

Flashback at SFMM. Finally we can ride this thing without any of the head banging. I heard that there is also a Windjammer recreation.

Another shot of the "Clippy Coaster"

Intel Inside coaster car, going up into a tunnel

Intel Inside car again

The station platform

The mid course brake run

"It looks like you're riding a coaster. Would you like help?"

The Editor

Here are a few basic tracks that I made in the editor. They are nothing fancy, but show what can be done.

Boomerang Coaster - A simple launched ride

Out and Back coaster - One of my first NL track designs.

Dive Machine - A NL ride with a vertical drop, many trains, and several inversions

Launched Multi-looper - Multilooping coaster that starts out with an Incredible Hulk style launch tunnel, which fires when the train is halfway up.

Hyper 2 - An out and back hyper coaster

Launched Mega Coaster - One of my first recreations that would probably be impossible to engineer in real life.

Portable - My first attempt at creating a portable coaster

Bushfire - A B&M style sit-down with several unique inversions including an incline loop and a pretzel.