Mario Adventure

"After Mario defeated Bowser in Super Mario Bros. 3, he and his brother Luigi began to escort Peach back to the Mushroom Kingdom. They were having a nice, safe journey until a Bob-omb fell from the sky!

Luigi looked up and to his surprise saw an enemy he had never saw before! It looked like a Lakitu, but it was black with odd eyes. He claimed to be Warkitu, a mutant Lakitu.

Mario got into his usual stance to take down this "Warkitu". However, Warkitu started to throw more Bob-ombs on the ground. Peach ran behind Luigi for safety while Mario tried to dodge the bombs, but Mario was hit and knocked out cold...

Frog Suit (BAD LAD): While playing a stage: Press B A Down Left A Down
P-Wing (LUB DA DD): While playing a stage: Press Left Up B Down A Down Down

When he finally came to, he found himself in an odd world. Fortunately, Toad found him just in time to explain what was going on. Toad told that Bowser had stolen a powerful crystal that magnify the natural forces of the world. Everything had mutated. Some of Mario's enemies had become more powerful!

However, Mario's abilities also became more powerful! Toad explained that the crystal's power worked for both good and evil. Mario obtained a nearby Fire Flower that changed his clothes to an unfamiliar orange. Mario found himself jumping higher than before, and his fireballs moved in a straight line!

When they came in contact with an object, they didn't disperse, they continued going! Mario smiled and new that with these new powers, he must set out on another adventure in this strange new land to restore peace and find out what happened to Peach and Luigi!.

Invincibility (RUBBA DUB): While playing a stage: Press Right Up B B A Down Up B
9900 Extra Coins (SARSLAB): While playing a stage: Select A Right Select Left A B

Mario travelled to the usual place that lead to Bowser's world, but the entrance was gone! Not knowing what to do, he asked Toad what could done. Toad explained that the only way to reach Bowser's Castle is by warping there. So Mario journeyed to the Warp Zone. On his arrivael, he saw there were giant locks blocking the path to the warp pipe to Bowser's world.

He asked a local who had put them there. The local explained that Bowser placed the locks there and hid the magic keys to them in the seven worlds that can be visited from the Warp Zone. Mario thought, no sweat, he would just go find the magic keys and unlock the locks.

However, little did he know, Bowser had hidden the keys very well and guarded many areas to throw Mario off. And to make it worse, each of his kids had re-stolen the wands, which would be needed if Mario were to activate the magic needed for the keys to work. A very complex situation laid before Mario. He knew he had to do it. So packing a bag for collecting coins, Mario set off on his adventure..."

-DahrkDaiz

New features:

• You got infinite lives.
• Mario Adventure includes its own custom palette for graphics rendering.
• New enemies with their own new AI patterns.
  
• Gain two cosecutive items and the first one is stored in the box. Pressing [Select] will use the item (or switch it with the current one if you have one in use).
• You no longer get 1up for reaching 100 coins, instead you can have up to 9999 coins.
• Instead of getting free power-ups from Toad's Mushroom Houses, you must buy a chance to get them for 300 coins.
  

New worlds:

• Weather effects, rain and snow, day and night.
• There are 7 worlds which Mario can visit in any order. Each world has a key hidden somewhere within it.
• After finding all 7 keys, Mario can access the 8th world to win the game.
• Almost all levels end with a Boom-Boom battle.
• The warp whistle takes you to a special level on each world which contains power-ups and other bonuses.

New power-ups:

• Gold Mushroom, is worth 50 coins.
  
• Coin Multiplier, for one whole level, any coins you collect (not including Gold Mushrooms or the coin bonus at the end of the stage) will be multiplied by a determined factor. You can use multiple coin multipliers to build up a higher and higher multiplier (using 3 coin multipliers can get you up to a 15x multiplier!).
  
• Magic Mario, which can stomp on more enemies than otherwise possible, shoots extremely powerful projectiles, and can take a few hits before losing the power-up.
• Invisible Mario, can temporarily go behind any background on a level. Pressing [Down] + [B] activates his power for a limited time.
• Fire Fire Mario, is just like Fire Mario, except he throws straight fireballs that can go through walls and he can jump higher!
• Kuribo’s Mario, not a new power-up, but the shoe doesn't go away when finishing a level anymore. You can even “store” it and “retrieve” (like taking it on and off) it at any time by pressing [Up] + [B].

Unlock World 8 + Unlock all locks (DD LUBS ALL): While playing a stage: Press Down Down Left Up B Select A Left Left If done correctly, you'll hear a coin sound. Reset the game and you'll see world 8 accessible on the Warp Zone.
Download:
Mario Adventure (NES Rom)
FCE Ultra v. 0.98.12 (NES Emulator)
Music Test: On the title screen (when it says Press Start) press: Up Up Down Down Left Right Left Right B A Select and "Grassy Hills" should appear. Pressing left or right will change the track, pressing A will play it.
Mario Adventure: The Best NES Game Hack of All Time
An Interview with DahrkDaiz, Creator of Mario Adventure
Mario Adventure in 56:01 by Olli Uuskoski (aka. Kyrsimys)
(The movie was made using an emulator with savestates and slow-motion. It's meant to show the game pushed to its limits.)

Edit:
Arrgghh... after spending alot of time to finding out every detail about Mario Adventure and summarizing it above, I found this link below with a complete FAQ.

Mario Adventure FAQ