Happy 7th birthday Zero Time Dilemma!
And also, this is the last part of a trilogy so it is easy to pick up for any new handheld gamer, wink wink, nudge nudge. It even comes in 2/3 package on Steam, with the first two parts, 999 and Virtue's Last Reward in one.
Make Kotaro Uchikoshi happy and play more than AI: The Somnium Files.
(and if you can go really old, play the Inifinity visual novels)