People have only just begun playing Prime 3, so it's hard to decide what the trickiest parts are just yet. However, there have been a couple of doozies that, for whatever reason, have stumped plenty of hunters in their tracks. Not spoilers ahead per se, but they do deal with puzzles that you may not have reached yet.
Bryyo Cliffside - I need the Grapple Swing!
The first 24 hours of Prime time were filled with the cries of uninitiated Metroid players, each begging to know how to cross a gap that required the Grapple Swing. Thing is, the Grapple Swing is on the other side of the gap. Hmm, what to do? Well, eagle-eyed fans realized that a small piece of rock back underneath the door can be bombed off, opening up a path that cuts though the mountain and dumps you out on the other side of the gap. Also, there's a missile expansion in that same path - just let the glowy critters fly at you until they bloom into a floaty bubble.
Energy Cell 4 - how on Earth do you grab it?
As with the other two Prime games, Prime 3 sends you on a scavenger hunt for several items late in the adventure. This time around they're Energy Cells, large batteries used to power all kinds of machines throughout the galaxy. Most you will find through regular play, but there's a good chance that you won't have number four until the last minute. One location on the galaxy map, GFS Valhalla, contains many floating computer pods that contain the location and status of each one of these remaining Energy Cells - be sure you scan them all (it's rule number one, after all).
Number four, as the floating pod will reveal to you, is in a "hidden" location on Bryyo. Search the Bryyo map for a room with "hidden" in the title, and you'll stumble across the "Hidden Court." Sounds like a good lead, eh? Once you're there, you'll have to solve a rather long puzzle to get at it. It's also item-intensive, so it's a good idea to wait to do this one last anyway.
Land near the Hidden Court, then make your way to the Fuel Gel Pool. Scanning will reveal that this giant piece of golem head can be moved - so summon your ship, cart it away and backtrack towards Colossus Vista. For some reason your ship visor will say there's no available drop point, but there is, so scan it, drop the head onto the golem and watch it smash open your path. Grab the extra ship missile to the left, then head to the next room. It contains a spinner that moves a metal cage and bridge around, but you'll notice that only half the bridge is there. On the other side of the gap is another spinner, another cage and another section of bridge.
Head back to the ship, land at the Thorn landing spot and your way back to the North Jungle Hall. Once there, you'll notice that a giant hunk of machinery can be towed away by your ship. Do it, enter through the revealed access tunnel, which in turn leads to the other side of the extendable bridge. Complete it, cross it and head back to the Hidden Court, where your ship will drop the giant battery in place. Boom, you now have access to the most annoying Energy Cell in the game (plus a few extra missile expansions if you're scouting around).
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