For the budding game developer

Please, please never forget to approach game design with a VERY open mind.

If they see it, they will walk to it, even if it looks remotely impossible, they will still try to do it.

Invisible walls, bodies of water, forcibly turning the player around without any explanation, the quick patch solutions to modern gaming, we need to get rid of them all.

If you don't want your player going to a certain place or doing certain things, just simply don't feature it in the game.