Many simulations were very in-depth, study-level and so realistic that even pilots could use it for training. I eventually moved on to X-Plane 11 by Laminar Research at the time where the addon market for it was starting to boom. This is assuming that the addons are not abandoned by the developer. Whenever an upgrade was released for the addons, developers often made users pay an upgrade fee. The software was continuously updated breaking the addons that were purchased for the simulator. Later on, Lockheed-Martin picked up from where the ESP platform was left from Microsoft and released newer and improved versions as Prepar3d. Back then, FSX required very powerful computers and the poor performance made me return back to FS2004. When FSX was released, all those addons were not compatible with it and became obsolete. I purchased a large collection of addons back in 2009-2015 for Microsoft Flight Simulator 2004 of a large variety and with much money.
