As with all Metroid titles, Zero Mission has its fair share of hidden bounties and tricks to be found. Read on for all the secrets and bonuses the game has to offer.
Before finding the Hi-Jump Boots and bonus ability to jump while in Morph Ball mode, you can already propel Samus to great heights with Morph Ball Bombs. Simply enter Morph Ball form and plant bombs at a decent rate without mashing B. Eventually with practice you'll be able to send Samus straight up as the bombs continue to propel her upward - perfect for picking up items early or reaching areas not normally accessible without other special items.
Remember this trick from Super Metroid? Thanks to Samus' standard somersault jump, with practice you can scale up walls of any height as long as they remain flat enough.
A normal somersault jump can be performed simply by holding left or right while jumping. If you somersault jump into a wall, then quickly press the direction away from the wall and jump again, Samus will kick off the wall and jump up higher.
Definitely a trick you'll need in any sequence breaking shenanigans you get yourself into, the only downer is that the Space Jump renders this trick useless, but it can still come in handy for the roughly 70% of the game you'll be without the Space Jump.
Normally the game directs you to hunt for the Varia Suit in Brinstar after scoring the Hi-Jump in Norfair. But all you really need to reach it is the Power Grip, Ice Beam and plenty of patience.
Head up to the chamber below the Varia Suit's location in Brinstar to find the small room deserted save for a single Waver. This little fella's the key to reaching this item early. Break through the ceiling and climb up quickly while avoiding hitting the Waver.
Now for the tricky part. Stand to the right of the damaged blocks and carefully shoot down at them diagonally to clear open a section of the floor large enough for the Waver to squeeze through (two blocks should be enough). You'll need to be very careful and avoid freezing the Waver by mistake, if you do simply exit the room and re-enter to try again.
Eventually once you manage to lure the Waver up above, wait for it to get into position above the crumbling blocks on the left half of the room then freeze it there. Climb atop and use it to reach the rocky ledge up on the left wall.
Now for the next tricky scenario. Shoot out the covering blocks directly above you, then quickly bomb-jump your way up to the door above. Once you make it up top go inside and carefully cross the acid-filled corridor to ultimately reach the Varia Suit.
This might take a while to successfully perform, but it saves you quite a lot of time in the long-run, so it's a great trick for speed runs.
Usually you'll pick up the Screw Attack after returning to Norfair upon conquering Ridley (a Morph Ball Launcher will send you straight up to it). Luckily there is enough room nearby to build up the Speed Booster's charge so you can reach it without using the Morph Ball Launcher. Firstly, head for the tall green segmented shaft near the Screw Attack's chamber (keep going left past the Hi-Jump's room and beyond the Save Room to find it).
Once inside, descend down one level and use bombs along the floor to discover where the Speed Booster blocks are (they're near the left side of the chamber). Go left to discover a long winding corridor filled with three pipes small enemies launch from. Cross to the left and begin the run back to the right. Keep firing as you go to blast any foes launching from the pipes, then as you pass through the door and the Speed Booster kicks in quickly crouch.
Back in the green segmented shaft, quickly step forward into position along the column of Speed Booster blocks and Shinespark directly up. You'll soar to the top of the shaft and arrive up at the Screw Attack's area. Simply head left and cross the corridor to find the Screw Attack waiting.
Much easier alternate method:
Very special thanks to cylex7 and Amaroq for this tip. Nintendo have been very sneaky trying to fool us with the Speed Booster method, but there's a much faster way of reaching the Screw Attack's chamber.
Instead of using the Speed Booster method, head to the segment of the green shaft right next to the adjacent Save Room. From there, stand next to the left door (with it closed) and fire four Missiles straight up. There's a column of Missile blocks hidden above (conveniently covered by the Energy Tanks in the HUD). Break through them and simply Wall Jump up the shaft. Head left to eventually locate the Screw Attack.
Upon completing the game on any setting, a small Samus logo will appear beside the file on the main menu to indicate that you've completed the game on that save file at least once. If you start a new game via the New Game option, the map screen will display new information for you.
You'll be able to see a checklist of the items you've picked up in each area, as well as the total time you've been playing. All very handy for fast 100% item run-throughs.
An interesting and somewhat baffling hidden addition to the game is Time Attack Mode. To unlock it, you'll need to use a game file that you've already completed the game with so that the Samus logo appears next to the file. Press A on the file to display the option "Start Game". Then press the D-pad in this order:
The option "New Time Attack" will appear.
The game will play on Normal mode only and will give you a password upon completing the game along with your clear time and item percentage. What's the point of it you ask? Is it for some speed-run competition Nintendo were hoping to hold in the future?
Crocomire, you ask? Yep, people have actually managed to extract a complete sprite sheet of Crocomire from Zero Mission's rom, and he still looks very similar to his Super Metroid appearance. So it appears that either Crocomire was indeed initially setup for inclusion in the game and unfortunately didn't make the cut, or he still is in the game somewhere as a hidden boss yet to be found. All we can do is wonder, where on earth (or Zebes actually) would Crocomire have fit in?