I've just beaten the game 100% and here's what I think of the whole package. Here's the order of how I think the performance goes for each game: Sonic 1 > Sonic CD > Sonic 2 > Sonic 3 Version: Steam Sonic 1 plays almost exactly how you expect from the mobile ports. The sound is fine, and the game overall is fine. The biggest problem is that it has the known Retro Engine quirks with more strict crush collision, and other small quirks. Sonic CD also plays mostly the same as the mobile ports. I never played the steam standalone version, but I imagine it's also similar. Something I really disliked about the remastered Sonic CD which is still present here is how poorly some of the songs loop. The JP Boss music just does not loop correctly at all, and some other songs suffer from the same problem. Another nitpick I have is how the score tally waits for the "level complete" music to finish, which does not occur in the originals. This makes some transitions feel much slower. This too was present in the mobile ports, and I dislike it. I still dislike it now. Sonic 2 is where things get worse by a lot. The first thing you notice is that the ring sound effect is not correct. Some people already mentioned it, and I can confirm its presence. If you are a decent player you will notice something that you have to deal with during the whole playthrough: Tails. Tails have an issue where the function that he respawns after you are too far away from him is completely broken. This causes Tails to get stuck and jump constantly. It is so bad at times that you just want to mute the whole game. Hidden Palace is present but has no achievement or anything attached to it, so it's just... there. Special stages are annoying because Tails is still as useless as always, and you can't turn him off in Story mode, meaning you need to get the "higher difficulty" amount of rings vs Sonic alone, even though you most of the time end the special stage with tails having pretty much always 0 rings or less than 10. The biggest problem with Sonic 2 is definitely the tails problem, which seems to be a matter of fixing up that respawn functionality that they broke for whatever reason. Now the meat that most people just want to buy this for: Sonic 3. I think a lot already mentioned it, but it's not really good. The thing you notice literally immediately especially if you come from Story mode (thus play the games in order), is the quality of the SFX and BGM being much lower compared to the other games. I am honestly thinking it is even lower than what some base emulators offer, which is pathetic. FORTUNATELY, the Tails respawn issue is not present in Sonic 3, so Tails does not get constantly stuck over and over. I also heard Drop dash is the best in this version. Honestly, I've rarely used the drop dash, since I am used to just playing the game like the old-school versions. Retro Engine's more strict crush collision is the most noticeable in this game, and it's extremely frustrating. You get crushed constantly if you spin dash at places, spin dash quickly after a moving platform went high enough, and get crushed in general. After Sandopolis I was just really done and just wanted 100% the game and don't open it anymore. If you purely considered buying this for Sonic 3 then I personally wait for a sale or bug fix patches. Sonic 3 A.I.R or Sonic 3 Complete even are much more polished products, and Sonic 3 A.I.R (legally) only requires the steam version of Sonic 3 & Knuckles which... you can no longer get actually because SEGA pulled it down, but much cheaper than what Sonic Origins costs. If this does not get any bug fix patches than it's an incredible average product at best, and if this is what SEGA offers us during the wait of Sonic Frontiers, then I do not look forward to what a mess Sonic Frontiers will be.