It doesn't have to encapsulate the game to be relevant to it. A lot of the titles I'm seeing - Metal Gear Solid, Dark Souls, the Witcher, Okami, Mass Effect, Halo, Mario, Sonic - are not indicative, but still relevant to the game's content. And I think if you were to name games with the intent of describing them in the title - Jumping Plumber with Mushrooms Turtles and Dragonsaur, Defeat Bosses Get Souls Link Fire, Make Choices In A Rich Alternate Universe Then Be Disappointed, Magical Wolf Village Defence, Blue Hedgehog Running - it would make for some boring and stupid titles. As far as I'm concerned a word like Sonic - which refers to the speed of the main character - or Mass Effect - the technology underpinning the entire universe in question and which allows your powers and equipment to work, along with space travel - is relevant. Titles shouldn't have to explain a game to non-players to be 'relevant'.
Actual irrelevant titles are such as Brink, Mirror's Edge, Final Fantasy, Resident Evil, Crysis have nothing to do with the game whatsoever, or perhaps have a vague thematic link. At the moment the thread is practically devolving into every game name in existence.
And in regards to the Mass Effect and Souls series, Mass Effect technology is practically everything in the ME universe (from biotics to space travel) and the Souls games are primarily concerned with souls, Demon's Souls in the first one, and the Dark Soul in the second.