Super Mario Maker for the Wii U allows you to create your own side-scrolling Super Mario levels and share them online with the community. For me in most attempts that has meant a few misplaced pipes, a pile of stacked Koopa Troopas and a mushroom going the wrong way. However, if you have a genuinely creative streak (and possibly a pretty sadistic one too) you can create levels so twisted and complex that they would make Baby Mario cry.
In this video I have compiled a collection of five truly butt-clenchingly difficult user-made levels which somehow a handful of dexterous thumb-wizards have actually managed to complete.
Watch and be amazed at the skill of both the creator and player and then, if you are anything like me, feel immensely inadequate and have a little weep in the corner.