All essential information to learn the game, without going much into details

Good ending

The only way to get a good ending: collect 5 purple scrolls, find the secret entrance and kill the final boss. without the scrolls or not using the secret entrance, the game will loop back to first level.

Purple Scrolls

< TODO - add a video for each scroll

• Level 1 - kill the ninja hidden in the left rock (near the end)
• Level 2 - walk in the last water on the right side
• Level 4 - get 100% hit ration in Level 3 and get the purple scroll from one of the first 3 ninja on level 4
• Level 6 - top right corner of the second garden (go inside)
• Level 9 - top right coner, at the end on the wall

Secret Entrance

on the level 10, after getting on the 5th scroll, disappear 3 times in front of the statue.

I'm not so sure ,but I think you need to kill the ninja coming at you while waiting at the statue