I think most people have hit on what I was going to say. 'Cheap' difficulty. However, that can actually take on many versions. When playing an action game, this can be with respawning enemies or a scrolling screen with 'cheaply' placed enemies that divebomb into you at 'perfect' moments that are unavoidable, etc. Good examples of this would be Ninja Gaiden on the NES.
But then there's 'cheap' on RPGS, which can also take on a wide variety of forms, such as in turn based RPGS with enemies rising in difficulty to an exponential level in just one area (causing grinding) or one specific boss which is 10x harder than a previous boss for no given reason, etc. All these things don't add any inherent difficulty to the game aside from making you have to level your character more outside of the normal progression of the game.
Further still, some games, both action and RPG, can have just plain 'cheap' bosses that are nearly unavoidable or nearly perfect in their skills. And take dozens of tries and near flawless play, timing and perfect memorization to beat. These are just stupid and add NOTHING to gameplay, add nothing to the players satisfaction except frustration and do nothing but waste time.
Six upcoming games you should look into:
