TY the Tasmanian Tiger

This game is split up into 3 zones, A, B, and C. Each zone has certain requirements that must be met before you complete it and move on to the next zone. For zone A, you need to complete the introduction/tutorial level, 9 normal levels, and then a boss fight (against Fluffy if you haven't gathered that from the achievement title). Once you complete the boss battle against fluffy, you will complete zone A, the achievement will pop, and you will be able to start Zone B.

The missions themselves are pretty explainable, you are presented with a main objective, and need to accomplish it by getting to the end of the level via combat and platforming/puzzle solving. The collectibles are not required to beat the levels/zone, but it is recommended to get them if you are trying to complete the game, and going for the "No Stone Unturned" achievement.

For the boss battle, you beat Fluffy by first jumping around and avoiding the rockets she shoots at you. After she fires the rockets, she will stand still for a few seconds, so you will want to quickly get near her and charge up a power-rang via whatever control method you are using, and fire it at her. This will daze her, and then you can go in and bite her to remove a section of her health. Do this a few times, and the battle will be over.