The dim dot where the notifications usually are and the dimming of the battery and time icons seen during the play of Asphalt 8 above are intentional behavior during full-screen app usage. I have seen this same thing on my Nexus 7 (2013) while reading books in the Kindle app, and it also replaces the three main Android softkeys at the bottom of the screen with dim dots. The purpose is to reduce distractions when you are engaged with a full-screen app. Of course, this is not proper behavior on the home screen, as experienced by the OP.