Sonic Zone

Speed - A fast sonic game, with high-dashing action

Action - Not just simply completing levels. A good story line with certain parts that are exceptionally better

Attacks and Combos - combat with combos for more action-filled battles

Guns and Vehicles - Equipping weapons and riding vehicles ( Shadow the Hedgehog Style )

Team Action - Playing with more than one character at a time ( Sonic Heroes Style )

MiniGames - do i have to explain this ??

Exceptional Boss Battles - How i hate it when boss battles are just regular battles - only the enemy takes longer to be beaten !!! I just love those boss battles that you never forget. you know ... destroying the boss in an original way. You know what I mean !! Destroying certain parts of him first, using the scenery against him, countering his own attacks, hijacking him ....

Unlockables - just about my favourite part in sonic games  ;D Unlocking abilities, chaos emeralds, gear etc.

Puzzle-Like levels - Levels which require more than simply completing them. Like, pressing switches, solving puzzles, opening doors, etc ...

Customization - I'm not sure if there's a sonic game out there that has this, but it would be cool if you customize character appearances, moves and gear.  ;D

Anyway, my five are :

Speed
Attacks and combos
Exceptional Boss Battles
Unlockables
Customization

but i do like the rest, except for puzzle like levels !! To hell with them   :D

Speed and action are necessary, good bosses help, and unlockables are always fun.

Speed
Action
Mini Game
Boss Battles
Unlockables

I like the idea of a customizable sonic game! Create your own character and levels! Thats what I liked about SRB2! ;D

Speed
Action
Attack and Combos
Team Action
Unlockables

A blue hedgehog that runs into things

Speed is one of the things that make sonic games fun and action is important too combo's make the gameplay much more satisfying and unlockables do too and customization would definitely  be awsome :3

Speed 
Attacks and Combos
Puzzle-like levels
Customization
Unlockables

I hope SEGA makes more aceptional games in the future

Good music!

First 4 and Custom...hmm I chose it but I need to be aware no one abuses it and says it's a FC. cause it'll be a recolor.

=Please don't bump topics aswell too :]=

Speed, Speed, Speed!

No sonic game can go without speed. Whether it's a large-scenic straight or a lot of loops, jumps and platforming, or even defeating enemies and bosses, it must all be fast. All adrenaline-pumping action that keeps you on your toes and wondering what's around the corner!


Action

Action is a must. Constant button pressing; constant interaction and movement; challenge and skill, it all has to be part of the mix. Whether it's a good cutscene worthy of some john woo film or if it's a piece of gameplay you wanna do over and over again because it's so thrilling!


Mini Games!

Want something a little different to spice up the gameplay? Mini-Games often do the trick. whether it's part of the main game or just an added extra, it doesn't matter. For anyone who's played for example: mario and luigi games; you'd know that changing the flow of the game and changing the way things happen is A-OK. Put in some variety!


Brilliant Memorable Boss Battles!

Must, must, MUST! You want to have some multi-staged, challenging and sometimes outright difficult battles. Something that gives you such a sense of achievment when finishing! not some repetetive hit-three-times-and-it's-over battle, but one that's WORTHY of it's own act! heck, make it cinematic and put in some interactive quicktime sequences too! XD
Of course, make sure it doesn't change the flow of the game, unless it ties in with a Mini Game


Puzzles!

How boring is it to be able to ace every level without busting your mind as well as your fingers? Very. Put in some challenging puzzles and spice up the game. heck, maybe some (only a little) backtracking?
Make it so you need to push a couple of switches or hit objects in certain order, or maybe even take specific paths. those with a weak mind dare not continue!

And to add in another: Story.
It deserves it's own section even if it ties in with the others. Having a game with a story is a bonus, something that keeps your play sessions large and you coming back for more during your first playthrough. Make it immersive and fun to watch! ^^

Anyway there's my say, sorry for the big post!

-DF! :D

I choose alot, but speed is always the best vote

As windle said

QuoteA blue hedgehog that runs into things

That's all we need to know