Here is the thing, if you download a game and open it with winrar you can se everything. So, how can I avoid that someone do that and solve a puzzle?

Thanks,

Write really obscure code...

To be honest, I don't think you can prevent it. I don't know if most people know you can simply unzip the file anyway.

It's like the original choose your own adventure books where you kept your finger in the page in case your decision led somewhere you didn't want.

I'm sure the author would have preferred it didn't happen. Equally the author must have been pleased that their creation was being experienced and enjoyed in whatever way people chose. It's nice to know you have an audience.