
Thankfully, Namco Stopped Numbering Sequels at Ace Combat: Assault Horizon, in part because, like X2/Joint Assault, that game is set in a different continuity from the numbered games.


The series contains six numbered games (of which 1 and 2 weren't originally part of the main continuity, and 3 is set after 04, 5, and 6) and five oddly numbered ones: Advance (prequel to 3), Zero ( prequel to the entire series and, more specifically, 5), X (released before 6 but set after it the "X" here is not the Roman numeral for ten either), Xi ( interquel to X the "i" is presumably indicative of the game being developed for iOS, meaning the "Xi" shouldn't be read as the 14th letter of the Greek alphabet), and X2 (which was eventually stripped of the "number" because it had nothing to do with X except the platform).
