Tunnel is a delivery system for the content distributed in cartridges. There's not really any point to running Tunnel without a cartridge. The Tunnel engine is built to frame cartridges with a certain personality, but the cartridges themselves are the objects of desire.
Playing a Tunnel Cartridge
Tunnel is designed for the web, so playing a Tunnel cartridge is effortless.
Loading the cartridge at a web server is as simple as typing the URL into a browser and pressing Go.
Tunnel uses the WebAudio API, which will require iOS users to turn their Ringers on to hear cartridges.
Cartridges are organized in layers. Each layer is a convergence of a looping sound clip and 4 semitransparent image slides with optional background colors. Layers are stacked in fixed order and the cartridge entry point is at layer 1. Layer 0 is the control layer, partially reserved by the engine.
The top half of the screen is a button moving the user outward.
The bottom half of the screen is a button moving the user inward.
These are the controls for traversing a Tunnel cartridge.
If a cartridge has standard labels on it, there will be a display showing the cartridge title and a number of hyperlinks.