I think there should be not only a Special Stage and a Bonus Stage, but also an idea that I came up with: A Challenge Stage.
If you finish the stage without losing any lives, when you run through the Signpost of the stage's end, the character will run in circles around the signpost gathering speed and then is teleported to a Challenge Stage. In that stage you can collect monitors to be used at the next Act. For instance: At the Challenge Stage you got a Flame Shield and a 10-Ring monitor. When you begin Act 2, you'll have two icons at the bottom of the screen, which are those two items you got. Pressing a certain button will give you 10 rings and another button will give you the Flame Shield.
I still don't know how the Challenge Stage will work. Maybe we can ripoff the Sonic CD Special Stage and instead of UFOs, Eggman badniks holding the items. It would be pretty challenging (duh) and getting the items will be a hard task. You can only have two items with you. If you get more than two, after you finish the Challenge Stage, you'll choose only two of them to be with you. You cannot keep the items you got in the Challenge Stage for other stages. After you got them, you can only use in the next stage you'll be at. Also, Challenge Stages will give you some awarding points.
Also, I like the Golden Motorbugs idea. But I don't think we should only restrict to Motorbugs. We could have some other golden enemies which are slightly different than the normal ones. Some of them, depending on how convenient to the puzzle design involved on reaching them and killing them are, could have multiple armors (needs more than 1 hit to kill), different ways to attack and move than the original badniks they were based on, etc.
And, another idea I threw in the Sonic 4 development forum: Fang/Nack would appear at a certain part of a level, depending on how much Chaos Emeralds you have. For example, you're at Blue Mountain Zone and you just got your 4th Chaos Emerald. He will appear at a certain part of this level as a mini-boss. He, however, won't steal your C.E.s if you lose to him (that would be too much of a pain on the ass if that happened...) but if you defeat him, you'll win some major bonus points or he would drop a 1up or a really useful monitor. If you lose to him, he'll not re-spawn at that place again and you lost the chance to win some good points.
2 Chaos Emeralds: He'll appear with his Pop Gun, running, jumping high with his spring tail, and shooting at you like he doesn't have to reload anything.
4 Chaos Emeralds: He'll appear with a small machine with a spring which can jump higher than before. It shoots two-way projectiles which bounce off the walls much like Gemini Man of the Megaman series. It also takes more hits to defeat him.
7 Chaos Emeralds: Fang this time is for real. A floating machine that's really alike the other one, that flies and teleports really fast, it has 4 sattelites which provides protection and can shoot many kinds of different projectiles. From homming missiles to shockwaves. When he's almost defeated, it will try bashing you with full-power destroying the machine in the process.
This post has been edited by Rave: 24 November 2008 - 09:12 AM