-Estimated achievement difficulty: 3/10
-Offline: 12/12 [200/200]
-Approximate amount of time to 1000g: 5 hours
-Minimum number of playthroughs needed: 2
-Number of missable achievements: 2 (Emerald related achievements)
-Glitched achievements: No
-Do cheat codes disable achievements?: No Cheats
-Extra Equipment Needed? No
Sonic & Knuckles is a port of the 1994 Sega classic. The achievements are pretty straight forward and won't give most gamers many problems.
You will need to complete the game twice, once with each character. You will unlock Sonic Finale for Sonic and Knuckles Finale for Knuckles for doing this. As soon as you start with your second character you will also get Two Sided.
You will get Fun Guy, Grease Monkey, Desert Runner and Hot Feet as you progress through the game the first time. You should also be able to get Extra Hedgehog by collecting 100 rings without losing any during this run.
Enter a special or bonus stage by jumping through the stars after checkpoints (only appear if you have at least 50 rings) to get Extra! Extra!, and collect enough rings when in there for Please Continue.
Follow the guide to make sure you collect all of the Chaos Emerald, unlocking Chaos Emerald for your first and Gettin' Super when you have all seven.
If you still need anything now just play through again if you need anything. I missed one of the Chaos Emeralds on my first run, even when using the guide, just take it slow and make sure you get them.
This is a pretty easy game to complete, for one it doesn't have any of the speed run challenges some of the other Sonic games have. As long as you get the Emeralds, this should be done in under 5 hours.