Enterprising gamers have come up with a way to squeeze all sorts of new and destructive fun out of the Crysis demo by tossing in the game's entire arsenal of weapons and vehicles.
A report on Rock, Paper, Shotgun explains how gamers are continuing to hack the demo, and that the most recent result of those efforts is a new map generated from material found later in the game. The map includes not only guns and explosives, but also tanks, boats and even helicopters, plus an appearance from one of the game's mysterious alien bad guys.
In order to take advantage of this, the new map must be downloaded and extracted into the game. Starting a new game will lead players on the same path as the original demo, up to the discovery of your tree-bound (and well-gutted) associate; soon after that point, however, players will come across a table of equipment as well as the alien enemy, and just past that, the guns and vehicles.
The new map may spoil parts of the game, and all original files should be backed up as adding the new map will render the normal demo unplayable. More information, including detailed instructions and links to the necessary files, are available here.