I'm in the middle of adding unlockable levels to my game,
Shade, and I wanted to get a sense of what players expect. Here are some of the ideas I have for how to approach unlockable levels:
* Present some sort of "locked" level without any explanation, i.e. just a padlock on it
* Present the player with the above and clear instructions to follow
* Present the player with the above and a riddle or hint but not a complete explanation
* Don't show anything but let the user find it through playing
Obviously some or all of these approaches have been tried before, so I wanted to hear what your preferences were as developers and gamers.