When comparing Garry's Mod vs FlightGear, the Slant community recommends FlightGear for most people. In the question“What are the best games on Linux?” FlightGear is ranked 23rd while Garry's Mod is ranked 55th. The most important reason people chose FlightGear is:
FlightGear has scenery that contains environments to fly in from the whole globe.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro The games mechanics and mods allow for ridiculously funny gameplay
You can do some really crazy things in this game thanks to all of the community mods available as well as the built in, in game tools. Pretty much any scenario can play out in the game, if you so desire. Of course the winning combination of funny tends to be when players are just goofing around.
Pro Tons of community made add-ons allows the game to continually grow
Garry's Mod has a wide variety of community made add-ons, which deeply extends the games content and versatility. Pretty much, if you can think of it, someone has probably already made it.
Pro Worldwide scenery
FlightGear has scenery that contains environments to fly in from the whole globe.
Pro Free and Open Source
All code written for FlightGear is opensource and available for anyone to use.
Pro Crash animations in some aircrafts
Pro It has world-wide multiplayer
Pro Live cockpit
Pro A lot of aircrafts to add
Pro It has amazing graphics
Pro You can almost recreate real incidents
Pro No bugs
Cons
Con It has nothing to tell as a campaign. Tastes like void, that is "meh".
Con Previously free to download
Garry's Mod used to be a free download but it is now a paid game on the Steam store.
Con Tons of bugs
At least in earlier versions.
Con Not as graphically advanced as commercial competition
Con Getting stuck upside down
After a crash a pilot may be stuck in an upside down position with no way to recover.