There are two series of flight sims that have been very popular, the main one is MS Flight Sim by Microsoft, it started with FS 98, and was improved and re released with improved models, engines and world over the years, the two latest and most uses are FS2004 or also called FS9 and FSX the last in the series because Microsoft closed ACES studio that made them all a little while ago..tho some of the former ACES staff have reformed a working studio. The MS flight sim world is very detailed, and has most of the working airports of the world..it is a flight sim, not a fight sim so there is no combat but you can indeed fly just about anything that has ever flown from planes of all types from all periods, with very detailed flight characteristics, cockpits, interiors and liveries..and you can add working AI planes from all of the major airlines and military types too. You also can add on sceneries that may not be part of the base content, and more is made all the time.
The Combat flight sim series by Microsoft was called Combat Flight sim and was also re released over the years with improved engines the last being CFS3, it is lame compared to the most modern flight sims including IL mentioned above which is the best out now. So you have a lot to choose from.