FlightGear

Program: FlightGear

License: GPL

Description: A flight simulator.

Website: https://www.flightgear.org/

Other: This request was denied back in 2009 because 250 MB was seen as unreasonably large at the time: https://portableapps.com/search/node/flightgear. The most recent Windows binary, v2020.3.11, is 1.9 GB and can be downloaded from https://sourceforge.net/projects/flightgear/files/.
A normal FlightGear installation uses "%APPDATA%\flightgear.org" and "%USERPROFILE%\Documents\FlightGear"