Tank-o-box is the typical arcade game in which you must defend your base with a tank. The objective of the game is to defend your base while destroying all enemy tanks before they destroy you. You will face different tanks, some of them are tougher than others and require several shots to be killed. As you progress in the game without being killed, you get more powerful, but if you die, you lose all the accumulated points and you come back to the original form. You also can get stronger by grabbing the power-ups that appear from time to time, which help you recover your health or get stronger in a snap.
Unfortunately, the game only includes one mode, but it allows you to play with a friend. The controls cannot be customized, but they are very comfortable and simple for both players.
Regarding the graphics, they are simple, but nice. You can play in full screen or windowed mode, and the levels are all different, featuring different scenarios. Sound effects are average and the music is suitable, but very repetitive.
In short, Tank-o-box is an enjoyable game which doesn't include anything new or impressive, but allows you to play with a friend.