Operation Rainfall, commonly known as oprainfall, was a video game-oriented fan campaign founded to promote the release of games not available in North America.

[2][3] Xenoblade Chronicles, developed by Monolith Soft, was an entry in the Xeno series, initially announced as an original project dubbed Monado: Beginning of the World.

[2] Xenoblade Chronicles and The Last Story were chosen for their genealogy, while Pandora's Tower was selected due to its unique mechanics and the fact that it was also published by Nintendo for the Wii.

[3] Operation Rainfall gave itself an eighteen-month deadline, with the conclusion of their campaign planned to coincide with the release of Nintendo's new Wii U home console in November 2012.

[3] The first phase of the campaign focused on Xenoblade Chronicles, with a part of their campaign resulting in large numbers of pre-orders being placed for the game on Amazon.com under its placeholder name: the game reached #1 in the site's pre-order list, beating both The Legend of Zelda: Ocarina of Time 3D and the PlayStation 3 bundle for Call of Duty: Black Ops.

[25][26] In addition to popular and press support, it received favorable responses from Soraya Saga, the writer for Xenogears and Xenosaga, and Mistwalker.

[16] Zach Kaplan of Nintendo Life said that the campaign needed to make a clear mark, showing that the success of the then-announced Xenoblade Chronicles was not a fluke.

[27] In a later feature for the same website, Thomas Whitehead said that the otherwise niche and slightly unremarkable Pandora's Tower had been granted a level of mystery and anticipation among fans through its inclusion in the Operation Rainfall campaign.

[31] Later, in their press announcement concerning Pandora's Tower, they acknowledged that it was a game with a "vocal" fan base, but did not mention Operation Rainfall by name.

They also stated that it was the positive sales and fan efforts for The Last Story that prompted them to release the game in North America.