Sonic the Hedgehog Pocket Adventure

A side-scrolling Sonic the Hedgehog platformer for SNK's Neo Geo Pocket Color, released late 1999-early 2000. The level art is mostly based on the Genesis version of Sonic the Hedgehog 2, while the music is primarily taken from Sonic 3 & Knuckles.

It was developed by Dimps, who would go on to develop other games starring Sega's prickly little mascot, such as the Advance trilogy, the Rush titles, the PlayStation 2/Wii versions of Sonic Unleashed, Sonic the Hedgehog 4, the DS version of Sonic Colors and the 3DS version of Sonic Generations..

Tropes used in Sonic the Hedgehog Pocket Adventure include:

• Airborne Aircraft Carrier: Aerobase Zone.
• Alliterative Name: Cosmic Casino.
• Art Shift: In Gigantic Angel Zone, Eggman starts using his modern clothing. When he starts the battle in his machine, he's suddenly in his classic clothes again, but then he runs off in his modern clothing once the battle is over.
• Bonus Level: The Special Stage.
• Casino Park: Cosmic Casino.
• Dummied Out: Tails.
• Eternal Engine: Secret Plant and Gigantic Angel Zones.
• Green Hill Zone: Neo South Island Zone.
• Let's You and Him Fight: Seems Knuckles won't give Sonic his Chaos Emerald without having a little brawl first...
• Megaton Punch: How Sonic gets into Sky Chase Zone.
• Nostalgia Level: This game is made entirely of Nostalgia Levels. Particularly interesting in this regard are Neo South Island Zone and Gigantic Angel Zone, which are pretending to be different Nostalgia Levels--Neo South Island is Emerald Hill disguised as Green Hill, and Gigantic Angel is Metropolis dressed up to resemble Scrap Brain.
• Pinball Zone: Cosmic Casino Zone.
• Recurring Boss: The "Egg Hammer Tank" from the Advance series first appeared here. Some other boss concepts are also reused in the Advance series, not to mention that you'll fight Knuckles and Silver Sonic during the game - Silver Sonic having Mecha Sonic's moveset.
• Soundtrack Dissonance: The musical choices start to get a little off in terms of appropriateness following Cosmic Casino Zone, such as placing the jumpy Mushroom Hill BGM (Act 1 to be precise) from S3&K in act 1 of Aquatic Relix, which is modeled after the not so jumpy Aquatic Ruin Zone from Sonic 2. The most egregious instance of this trope, however, must go to the final boss battle, where the tranquil Sky Sanctuary BGM (also from S3&K) makes the epic showdown with Eggman a little less epic.
• Space Zone: Last Utopia and Chaotic Space Zones.
• Super Title 64 Advance: One of a number of games for this system with the word "Pocket" in the title.
• Underwater Ruins: Aquatic Relix Zone.