I haven't played the game since I was like 8 or something but the bits and pieces I remember about the beginning of the game was that you needed fly a plane somewhere but in order to safely land the airplane you needed to hire a ninja (at least I remember him having an equipable ninja outfit) by finding a scrap of paper and folding it into a paper airplane. You then needed to find a way into a castle or fort thing and I remember grappling hooks or bribing a local farmer with the prospect of flying the plane and cigarette for his clothes.
Also the manual had a tips section that required you to use a red lens type thing (kinda like the ones from the old 3d glasses) to read the hidden text. I'm not exactly sure if the game was a DOS game or an early windows 95 game but I know I played it sometime in the 90s.