Ideas are not a form of intellectual property. Complex processes and mechanics can, in some cases, be protected by patent. But a simple game design mechanic like the one you are describing cannot be protected under any IP system I know of.
It's possible that a combination of a certain mechanic along with certain visuals might combine to form a violation of 'trade dress' laws if your game was so close to another in appearance that it could be argued that you are likely to confuse potential customers into thinking they are playing someone else's game. But merely "jumping below a block and hitting it with your head to make some sort of bonus item sprout from it" is not enough for this to be the case.