Sonic Rivals and Sonic 3 Multiplayer

Let's see here:

Characters:
It's been said, but the characters in Rivals are all the same, bar special ability:

Sonic: Sonic Boom (boost)
Tails: Flight
Knuckles: Hammer Punch (SRV1) / Knuckle Slam (SRV2)
Shadow: Chaos Control (slows down time)
Silver: Psychic Control (alters enemy controls)
Rouge: I forgot the name, but it summons a bunch of bat bombs that make a shield. She can also shoot them at other players
Espio: Invisibility (forgot the name)
Metal Sonic: whatever the enemy has, will use Sonic Boom if there is no enemy

Stages:
The stages in Rivals 1 are pretty linear, albeit varied. Also pits everywhere. Meanwhile, Rivals 2 stages are Sonic 3 (single player) huge. Alternate paths out the ass, and nary a pit in sight (ok, there's like...5 in the entire game). Rivals 2 gets a special mention for using a Wild West themed stage.

Gimmicks are taken from all eras of Sonic games. From slot machines, to poles you can clime, to the jumping panels of the adventure games, the pipes of chemical plant, and there's even a teleporter in one of the stages. There's also a level where you team up with another character, and they'll use their powers to clear obstacles for you. As for frequency, you won't go 5 seconds without running into some kind of obstacle unless you're at the end of a level.

Bosses:
The bosses are basically Sonic Rush style, which is classic bosses on a 3d plane. I think all of the bosses of Rivals 1 take place on circular fields (except the last one). Rivals 2 changes it up a bit with two chasing bosses, a cave boss, two bosses where you have to use a stage gimmick to attack, and then tops it all of with a free falling boss battle. Come to think of it, I think the final boss of Rivals 2 may be the only one of it's kind. I can't recall any other free falling bosses.

It's generally six hits for the kill (8 for final bosses), but you have to get all 6 hits yourself, attacking isn't always direct, and you have to stop your rivals from getting 6 hits before you. If Metal Sonic (or Metal Sonic 3.0) is your rival, then it's a two on one battle. He's out to stop you cause he's working with the boss.

The single biggest issue with both Rivals games is that the physics are basically based on Sonic Rush/Sonic 4. Rolling doesn't do jack slag, and you need boosters to maintain speed. They DO have the neat feature hat you can cancel rolling by pressing up though.

 

Yes it would. Thanks.

I think Backbone has what it takes to design something along the lines of a proper Sonic 4. One only needs to take a look at the levels in Rivals 2 to see that. They'd just need to change up the engine to accommodate. In fact I imagine it was a proper platforming engine before Iizuka came along and added his "midas touch"