1. [Sun] The state of being heads down in order to finish code in time for a demo, usually due yesterday.
2. A mode in which video games sit by themselves running through a portion of the game, also known as attract mode. Some serious apps have a demo mode they use as a screen saver, or may go through a demo mode on startup (for example, the Microsoft Windows opening screen — which lets you impress your neighbors without actually having to put up with Microsloth Windows).