I couldn't say what is truly hard to find, but Darkest of Days and Civil War: Secret Missions are not uncommon.
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l2632&_nkw=civil+war+xbox+360&_sacat=139973&LH_TitleDesc=0&_odkw=civil+war+ps3&_osacat=0
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=darkest+of+days+xbox+360&_sacat=139973&LH_TitleDesc=0&_odkw=asterix+xbox+360&_osacat=139973
Asterix seems to be hard to find, however.