Sonic CD is based on an engine similar to Sonic the Hedgehog 1 (rather than Sonic the Hedgehog 2), but has been tweaked a LOT. The immediate difference in the gameplay is Sonic's 3 new abilities. The Spin Dash Attack (from Sonic 2) was added to the mix, as well as the Figure 8 Maneuver. The other new thing added was the ability to teleport through time, causing levels to have a different look to them, as well as various quirks. Using this time travel system, you can help cause "Good Futures." The quest for emeralds remains a big part of the game, but the bonus levels are VERY different this time around. On the hunt for Time Stones, you enter bonus levels just like in Sonic the Hedgehog 1 (50 rings at the end of the level, then jump in the giant ring). The bonus levels are completely original mode 7 play fields, where you must break all the UFOs in the field. To top it all off, Sonic CD has Time Attack mode, and a nice save feature which, at the time, was pretty rare for a game like this. The game lacked one major gameplay feature I was hoping for. Being brought up on Sonic the Hedgehog 2, I was itching to use Super Sonic, but that doesn't take anything away from the game.

        The graphics of Sonic CD are VERY colorful, detailed, and smooth. Sonic CD has a style all it's own, with graphics that no other version really seem to match. The enemies, and specially attacks in the game are all very well animated. One of the unique things done when extra space was involved with old-style CD games was FMV videos. The opening and closing to Sonic CD are nice anime videos with vocal songs ("Sonic Boom" in the American version). The videos do lack full screen, and aren't very high resolution, but even so, at the time, that was still very good.

        The audio in this game is another thing most Sonic games never matched. Sonic CD has very sharp, unique sound effects, and soundtrack light years beyond most Sonic games. I'm not sure what you'd call the style, but the soundtrack is one you'll never hear anything like ever again. It's amazing, and totally unique. The American Sonic CD and Japanese Sonic CD both have vaguely different soundtracks, and both were great. The American one is probably more appropriate for the American audience though.

        This rendition of Sonic is by far the best 2-D incarnation of Sonic there is, and if you enjoy a nice long Sonic game with huge levels, this is for you. Sonic CD leaves very little to be desired. Great graphics, a soundtrack rivaled only by Sonic Adventure 2, and gameplay that never fails… You can't go wrong, especially since you can probably pick this game up for anywhere between $3-15 used.