Singularly Datarific said:
Mechwarrior Series is built around operating giant walking tanks, and especially the 2nd and 3rd get the feel just right, as if you are driving a vastly complicated machine that actually requires a full keyboard (My joystick doesn't have enough buttons)
While I initially resented the changes made by Mechwarrior 4 (3 was the best interpretation of the Battletech rules), I came to appreciate them in the long run. While there were problems with balance at first (Most of the weapons were beyond useless and most people simply used the ER Large Laser, the ERPPC, the CLRM20, Gauss Rifle or heavy LBX autocannons), eventually the expansions provided a resolution. While the actual mech combat was enjoyable enough, looking back I think my favorite part of the game was the Mechlab. The combat was simply a way to test my designs.
In terms of other games however, there are a few worthy of note.
Battlefield (Series): The balance between vehicle and infantry tends to vary wildly depending upon the particular example in the series but a key part of what makes these games unique lies in the vehicles and their use on the battlefield. None of them are particularly complex to operate but most of them require a particular mindset and approach in order to be both useful to your team and survive for any significant period of time.
Battlezone (series): The games are ancient (the last entry in the series is over a decade old if memory serves) but still rank as some of the greatest games I've ever played. The game was essentially an FPS RTS and players were free to jump in a vehicle and lead the assault. In fact, such action was highly encouraged as the only way to deliver orders remotely required a rather expensive building.
Armored Core: The usual japanese take on giant humanoid robot. Each entry in the series has incredible depth when it comes to designing and building your mech, but unfortunately the game itself is rarely much fun. Later entries in the series finally made the control system resonable for a person but the most recent attempts have been, in my view, the least entertaining of the series.
Falcon 4.0: Truth be told I spent far more time with Falcon 3.0 gold but 4 is almost certainly the more acceptable game. Modern flight simulation with an anal retentive eye for accurate simulation. Famously in falcon 4.0 the only part that isn't fantastically accurate is the performance of the then (and possibly still) classified radar system in use in a modern F-16.
Steel Beasts: It's old and ugly but if there was ever a more accurate tank simulator, I have not seen it.