Sonic The Hedgehog 3

I got this one during the second special stage by making sure I got a perfect by collecting every ring in both the first and second special stages. (See the Chaotic Achievement for details).

However if you don't get it then, destroying badniks will award you with points as will completing the level with a certain amount of rings or time left... these will award you with lot's of points.

You will undoubtedly get this achievement through just playing the game normally, however if your struggling and haven't got it by the beginning of the Launch Base Zone Act 1, there is a method you can use to get lot's of points.

When you start move to the right through this little trap which will set an alarm off and cause these flying badniks to attack you, simply camp in that area and spindash (Down + A) and the badniks will keep spawning and you will automatically kill them - netting you points along the way!

I found this solution by accident, but it works like a charm. Every level has a time limit of 10:00, but if you finish at exactly 9:59 you will get a time bonus of 100,000 points.

Since you can save at any point, I suggest taking your time on an early level and letting the time build until you are close to a boss fight, and save as you approach 9 minutes and 59 seconds and have only one hit left on the boss. If you can score the last hit at exactly 9:59, you will get all three point achievements in one level, and this method is less frustrating than getting perfect on the 3D bonus stages in my opinion.