An oldie, but a goodie in the realm of tank simulations.
A long-time ago, Steel Thunder was THE tank sim. It's still a game that I dig out from time to time, and spend hours playing. The player has, at his disposal, various tanks ranging from the Sherman to the M1A1 of modern-day warfare. It's fun to change up your tanks, and see how well they do/don't perform on a given mission. While the graphics are certainly nothing compared to today's, it does offer what you want in a tank sim: various mission environments, the ability to do EVERYTHING involved in commanding a tank, lot's of firing, and cool explosions when you kill an enemy. A little fascination of mine has always been focused on sounds that programmers can get to come out of that pathetic little speaker in your computer, and these guys did a top-notch job on that! You hear the idle of the engine, your own gun's explosions, and you definetely hear A'LOT when you're being pelted. A good game for some quick, armored warfare.
Not much......a couple of additional training missions might have been nice, but that's about it.
The Bottom Line
Steel Thunder offers fast and furious gameplay that is well-balanced between realism and fun.