You drive the green tank at the bottom of the arena while enemy tanks patrol the upper half and fire down at you. Your turret always points at the mouse, so you drive with one hand and aim with the other. Clear every enemy on screen and the next wave spawns with more tanks; lose all three lives and the run is over.
Destroying an enemy tank is worth 10 points, whatever wave it came from. Each wave spawns three tanks plus two per wave number, so wave 1 has five and wave 5 has thirteen. From wave 3 onward tanks start taking more than one shell: red tanks die to a single hit, orange ones need another. You have three lives, each enemy shell that reaches you costs one, and there are no extra lives, so the run ends at zero.
No. They keep coming, with more tanks each time and tougher ones from wave 3, until you lose your last life.
Yes. Movement is on the keyboard and aiming and firing are on the mouse, so they never interfere.
Yes. On a touch screen the game shows on-screen buttons, and games played with a mouse work by tapping.