In Europe copyright issues have forced Atlus to change the action game's title.
Atlus didn’t release any details or hints about who issued a copyright claim against them for Attack on Titan but the official European Union trademark database (OHIM/CTM) contains details of the copyright filing and the subsequent opposition for Attack on Titan (CTM013347331).
PT Entertainment Limited issued the complain because of their game Titanbet and winner:
Timeline of events:
10 Oct 2014 – Trademark application by Kondansha Ltd for “Attack on Titan” wordmark under classes 9 and 28 (covering computer games and electronic games)
25 Nov 2014 – Application published for opposition with a deadline of 25 Feb 2015 for any trademark opposition to be filed.
25 Feb 2015 – Opposition filed by PT Entertainment Limited against “Attack on Titan” under grounds of “Likelihood of confusion”.
26 Feb 2015 – OHIM begins investigations into the validity of the opposition claim and informs Kodansha Ltd about it.
6 March 2015 – OHIM declares the opposition claim is admissible as it is based on an earlier right for “Titan”.
11 May 2015 – Expiry of ‘cooling-off’ period
12 May 2015 – Beginning of adversarial part of opposition proceedings
11 July 2015 – Deadline for submission of further material to substantiate earlier rights.