Building a super-hard non-insane level.

[AdrenalinDragon]

Don't have too much guesswork, but find a way of figuring out something may be hidden under a block, but Blobs and Walkers are fine, as long as they are used appropriatly. Try to make the level long, but with also lots of things to do in it at the same time. Also, making the level possible on a first try would also give you bonus points, plus giving the player loads of time when they are casually playing it.