Ok, if you ever want to experience a culture shock of biblical proportions, I recommend you play Sonic Generations, then Sonic CD. Both are available on steam, by the way.
Sonic Generations was a great game, even if the final boss was a bit confusing and the 3D platforming sections were a bit difficult to control- not the speed sections, mind you- although the last one might just be me being terrible at 3D platforming. The first three levels especially were made of nostalgia- and I absolutely loved the updated music for the first boss fight.
Then I played Sonic CD, and sweet Sigmar did I dislike that game. It came out after Sonic 2 but it was a big step backwards for the series. Mind you, I only played Sonic 1, 2 and 3&knuckles back in the day, since I didn't own a Sega CD, but while Sonic CD was released inbetween 2 and 3, the level design, music, special stages, technology and everything else about it feels worse than Sonic 1. Don't know if the Sega CD was just a bad system, I never really heard about it until now, but who in their right mind thought it would be a good idea to have players look for hidden signposts and machines in a game that is about reaching the goal as fast as possible?
Sure I can spend six minutes in each act trying to first find a "Past" signpost, then a spot where I can run fast enough long enough to do the timewarp, THEN find the hidden robo transporter and break it to get the good ending (if I do it in every single level), but this is a Sonic game, you're not supposed to take that long to finish an act. The time travel bit is a nice concept, but so very, very poorly executed. Of course I can skip the timewarping entirely and just focus on getting all seven emeralds from the special stages, but the special stages are horrible. It is a typical 3D game from a time when 3D just didn't work, and they shouldn't have tried to implement it. Sonic 1's special stages were fun. Sonic 2's special stages were fun, if a bit repetitive. Sonic 3's special stages were awesome. How could the developers fail so badly with the special stages after making two games where they worked just fine? Plus there's no super sonic reward, you just get a good or bad ending, which are almost identical anyway.
Anyway, I finished the game in two evenings or so (which felt like three weeks), and I'm just disappointed. The metal sonic race at the end is more frustrating than it is challenging, and the music that plays during it is just terrible. The bottomless pit at the end of the final act is just plain stupid- a big section of bumpers, springs and disappearing platforms, which you need to cross a big pit and get into a small corridor- which is periodically closed off with a crusher. And no, you can't see whether the crusher is open or closed from where you jump at it, and no, you can't time your jump in the first place because you start your jump on a disappearing platform, and the only way to get there is to launch yourself via multiple springs, and MAYBE you even get catapulted into a moving bumper, so there's no way to end up where you want to go. And if you make it to the crusher? Congratulations, nine times out of ten it is either closed or closing, meaning there's a big chance you'll either fall into the bottomless pit or get crushed underneath.
But if you succeed, you'll be treated to an annoying miniboss (three lighting bugs you can only hit at very specific times), and an insanely easy end boss right afterwards. Up to act three I was considering replaying the game after finishing it in order to get the good ending, but at this point I'm just happy to be done with it.
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Playing Sonic 4, episode 1 now. It is fun.