The short story: Your goal is to destroy your opponent's tanks by entering the correct power and angle values for shooting your projectiles. You earn money after each round based on your aiming skill, enabling you to buy different shields and weapons. But there's much more to it, and not everything can be mentioned here. You can choose between simultaneous, sequential and synchronous gaming mode, as well as the weather conditions, gravity, etc. But I recommend you leave these, as well as all the other options from the rather abundant set of options as is, for now. You can try modifying them once you get bored with the game, and there's a good chance that it won't be any time soon.
A multiplayer game mode is, of course, supported for up to 9 players. The default graphic resolution is a bit unusual but nice: 360x480 (256 colors). Scorched Earth is not the first game of its kind, but it has a certain "personality." Unfortunately, the full version is not available. I don't know if there is anyone left on earth besides the author who has the full version and is willing to share it. However, it's not something to be concerned about, since the only difference between the full and the shareware version is the availability of the seventh tank (there are six types to choose from). I don't know if Mr. Hicken still sells the game ... if he does, you might want to purchase the full version out of respect for him.