A highly prototypical demo, titled Metroid Prime Hunters: First Hunt, was included as a pack-in (now discontinued) with the DS launch on November 21, 2004 in North America, Australia and Europe. This demo was not released in Japan. First Hunt had a different layout to the lower screen, and a slightly different weapon system. There was a different default control method, in which the screens were transposed, and targets could be fired upon by tapping them with the stylus regardless of whether they were centered in view. The control schemes found in the final version were also available. The Power Beam had no charge function, and it had an ammo system. When Power Beam ammo was exhausted, the rate of fire slowed greatly.
There was also a “Double Damage” pickup that caused Samus to cause twice as much damage with each shot (which reappeared in the multiplayer battles of the final version of the game) and only two sub-weapons, missiles and the “Electro Lob” (similar to the Volt Driver and Battlehammer, it lobs and explodes on impact but also can impair vision). Three training scenarios were present, as well as a multi-card multiplayer mode. Some of the multiplayer levels from Hunters were included in the demo. – [info from Wikipedia]
[Thanks to Michael Cheek for the contribute!]