Woo! _-Ukiyo-_ requested this game so I'm doing it!

1. Undefined Fantastic Object was released on August 15, 2009 and is the 12th game (15th actually) in the Touhou Project franchise.

2. In addition, Touhou Hisoutensoku was released along with UFO, becoming the 12.3 (16th) game in the franchise.

3. Along with Reimu and Marisa, Sanae makes her first appearance as a playable character (originally the 5th stage boss of Mountain of Faith)

4. UFO is the only game where all the characters (including the playable ones) are holding (or has) in animate objects. I'm not kidding. Go look at the characters for UFO (Including the playable ones) and check it out for your own eyes.

https://en.touhouwiki.net/wiki/Undefined_Fantastic_Object/Characters

5. UFO is more oriented towards the element of Buddhism, as shown with Byakuren's description being a Buddhist monk.

6. The Palanquin ship at the end of the game was renovated into a temple which was named after Byakuren's brother, Myouren.

7. According to VGFacts,  "In the theme of stage 4, "Interdimensional Voyage of a Ghostly Passenger Ship", a Windows XP "pop" sound effect can be heard about 2 minutes in. According to series creator ZUN, it likely got into the recording by accident."

8. The name "Undefined Fantastic Object" is a reference to "Unidentified Flying Object" AKA a UFO.

9. Out of all the songs that ZUN made, he notes that the first stage and final boss theme were the important parts. (I need to listen to them again :P)

10. Going along with music, ZUN also notes that, according to the touhouwiki, "the stage 1 theme is always the first composed, so he put a lot of time into it in order to extensively test the game system" (oh so that's why the later stage themes sound so bland- nah jk)

11. There are some subtle references to the PC-98 touhou games, such as the player traveling down to Makai and a spell card that resembles one of Shinki's attacks.

12. In addition, some spell card names are references to other shooter games.

I think that's all I got.

https://en.touhouwiki.net/wiki/Undefined_Fantastic_Object

It's actually hard to find facts about these, but I managed XD

I might add more UFO facts when I have the time to.

In the meantime, REQUEST REQUESTS REQUESTS!!!