Benjamin's Flight, a set of new levels (and music and lovely narration) for Thomas Was Alone, debuted exclusively on PlayStation systems. Now, here the DLC is on Steam, for free.
You get to use a jetpack in it, so, yeah. Nothing more needs to be said about the subject.
Although, it is worth mentioning Thomas Was Alone is on sale. Fund it with the store credit you earned by flipping Steam Trading Cards, if you must. It's a real charmer.