I absolutely cannot name threads to save my life. There's been this thing in the back of my head about CD that's always slightly bugged me. It's not the level design per se, or the two distinct soundtracks, or its unusual and weird diversions from the codified classic Sonic formula that Sonic 2 created. It's more that the game boasts four distinct time periods, but they're used in a very uneven way. The way CD is set up, the present exists solely for you to go to the past. The bad and good futures on the other hand, are weirdly pointless: in the first two acts of each Zone, there is literally zero gameplay reason to go to the future--it holds no special collectibles, thing to destroy, etc. Act 3 always does take place in the future, but they are all extremely short and exist solely to hold the boss arena. So why can you go to the future in the first two acts? I guess just for the fun of it and messing around, but that still seems kinda pointless, because as far as I know the actual level design differences between time periods are pretty minor. If anything, the future posts do nothing but annoy you because you might hit one and then have to figure out how to get rid of it, which is extra great because the sole way of getting rid of it is getting enough speed to time travel and then not actually doing it. There's a huge amount of art and music on CD for time periods you barely go in. Even in the Act 3's, you spend like fifteen seconds hearing the future songs before you go to the boss. While the Sonic community has pretty heavily agreed upon 2 acts as the sweet spot for 2D Sonic, I honestly think CD should have been more like Sonic 1, where the third act is a decently long level in its own right before the boss (and also just not have future posts in the first two acts). Then, you can actually experience the future songs and art in an actual level and either enjoy your hard work or be reminded that you didn't do the proper thing in the previous two acts. That could have also let the two futures have more distinct level design; perhaps the good ones can have speedier level design while the bad ones are much slower, more platforming based, and have enemies in the way. In other words, CD would actually reward you for scouring the first two acts and destroying Eggman's machines with a speedy fun level or punish you with a slower more challenging level with much less flow. Alternate versions of a level are a thing I absolutely love in video games--everything from Super Meat Boy's Dark World to Mania's Act 2s often differing a lot from their Act 1s--so it's just annoying to me that CD has four versions of each level, but two are incredibly superfluous in terms of actual gameplay.