Jak and Daxter: The Precursor Legacy/Items and Hazards

Items

 * Orbs - These appear as mauve eggs with some writing on them. In the full game, these are apparently a form of currency. In the demo, the 150 Orbs present only count toward your completion goal at a rate of about 1% per 15 Orbs. Most Orbs are in plain sight, but some are contained in other objects such as Metal Boxes or the Blue Eco Device.
 * Power Cells - These are your main objectives in the game. They appear as glowing spheres with smaller spheres surrounding them. On Misty Island, there are 8 total. On the Progress Screen, you can see which of the 8 objectives you have completed. Power Cells count toward completion at 10% each.
 * Scout Flies - These appear as small helicopter-like objects. They do not begin in plain sight; instead, you need to open the red metal boxes they are in with a Handstand Dive. In the Demo, there are 7 Scout Flies that count for 10% combined or about 1.4% each.

Hazards
Health Meter deductions for contact are in Health Meter units in parenthesis after the hazard name:
 * The Fish (Fatal) - Surrounding the beach areas of the island is an invisible boundary line. If you swim past that line or fall into the water away from a beach, a large fish will come and swallow you whole. The only way to avoid The Fish once it appears is to get back within the boundary line.
 * The Fall (1) - Falls from high places can still hurt Jak. However, the only place this is observed on Misty Island in the Demo is the platform at the top of the long backbone bridge in the Sculptor's Muse Area. A jump straight off might be ok, but a double-jump will give Jak a harmful fall. The only way to avoid it is to not double-jump from that platform in the first place.
 * The Mist (Fatal) - The Mist only exists in the Mist Pillar Area of Misty Island. A fall from one of the pillars into The Mist is fatal. (Most locations in the Mist Pillar Area where this would be an issue would still fall outside the area that is safe from The Fish anyway)
 * Purple Lurkers (1) - Purple Lurkers move about in a gorilla-like fashion; that is, they can stand on two legs but move quicker by dropping to all fours. They only try to punch Jak and if successful, will stand up and beat their chests. Purple Lurkers can be killed with one normal punch or kick.
 * Skeleton Lurkers (1) - These are tall, bulky Lurkers dressed in skeletal armor. They carry clubs made from a large bone and swing their clubs at Jak when they're close. These require two normal hits or one hit while under the influence of Red Eco to kill.
 * Mud Lurkers (1) - These are purple and white frog-like creatures. They hide in several of the mud puddles around Misty Island. To attack Jak, they can spit out fireballs. If Jak is wading in the mud nearby, they will hide. To kill Mud Lurkers, Jak needs to attack them from the area around the edge of the mud puddle. Only one hit is needed to kill a Mud Lurker.
 * Dark Eco Boxes (1) - Yellow and grey boxes marked with a biohazard-like symbol. These contain the same Dark Eco sludge that turned Daxter into an otsel. When touched by Jak, they explode. Avoiding the boxes altogether is the idea here, since Jak can't outrun the explosion. Be careful when punching near a Dark Eco Box since Jak's punching momentum can easily send him into one by mistake.
 * Dark Eco Pool (Fatal) - The Dark Eco Pool is at the top of the stairs that appear when the Arena Area ambush fight is over. Falling into the Dark Eco in the pool, like falling into The Mist, is fatal.
 * Balloon Lurker Mines (1) - Attached to each of the Balloon Lurkers' balloons are two mines, one in front of and one behind the driver. To put it in Daxter's words "Rule Number 1: Always avoid the mines!". Also, the mines appear to provide weight to the balloon; attacking the driver is much harder once a single mine is detached from the balloon since he's higher off the surface of the bay.
 * Lurker Cannon Charges (1) - These are bombs shot from the Lurker Cannon on top of the Arena Area. If Jak enters the Arena Area ambush fight before stopping the cannon, these will periodically fall into the middle part of the arena. Run from these if one falls nearby.
 * Barrels (1) - These appear on the bridge between the top of the Lurker Ship and the balcony above the Arena Area in the following pattern: 2 rolling then 1 bouncing. Jump over the rolling barrels and duck under the bouncing ones (it is possible to time a run up the bridge to simply run under the bouncing barrel instead of ducking)