Actually Fleet Defender steered away from the older MPS Sims, it’s not player centric, and while missions are not randomly generated there are loads of variables that introduce a lot of randomness and variation to the same mission. So its pretty common that a familiar missions play differently every time.
Let me give an example: on the El Dorado Canyon campaign there’s a specific mission with a pair of Lybian MiG-23’s that might or not do a high speed low altitude cruise missile run against out carrier. You can be flying back home and arrive in shock only to discover your carrier has been hit.
Sometimes you can watch planes from other nations clash. It is quite common to watch Greek and Turkish planes skirmishes, and in the North Cape scenarios neutral Swedish Viggens can intercept you, other friendlies and even the soviets. If you don’t leave Swedish air space they’ll shoot.
The game is pretty accessible in easy mode, but you can customize the difficulty really well. Setting everything to Authentic mode is very hardcore and realistic as the simulation allows but also extremely rewarding.
When playing on Authentic mode the learning curve is really steep. Keep this in mind: until the release of the DCS F-14 module, Fleet Defender was the most complex F-14 simulation ever.