If you've played any of Valve's Left 4 Dead games, you'll know how the zombie hand (and fingers) played into each subsequent installment.
Artist VutiAru wondered if the still-unannounced Portal 3 could do the same thing and created this concept box art. According to VutiAru, it hints at a total new direction. That it does.
Yet, immature sex joke aside, it actually sums up the Portal games pretty well. If only there was a way to show the finger coming out of another hole.