Artillery is a cannon duel from July 1982 and one of the earliest examples of its genre on the IBM PC. It did not come out of a software company: it was written and distributed by members of an IBM PC user club in Portland, a community of enthusiasts gathered around what was then a brand-new machine widely regarded as strictly office equipment. Games like this are what PC gaming looked like before PC gaming officially existed.

The formula is now a classic: two players, one at each end of a randomly generated mountainous landscape, take turns firing a cannon. You enter an angle and a velocity, the shell arcs across the screen, and it either buries itself in a hillside or finds its mark. Wind bends every trajectory and can be steady or shifting, while the terrain is destructible, so the craters left by near misses gradually reshape the battlefield and open new firing lanes.
The clever touch is time pressure. Each player commands a gun company of a hundred men, and every turn one soldier deserts from each side; dither too long, cautiously bracketing your shots, and your unit simply melts away. Duels cannot be dragged out forever, and every round has to count. It is a small idea, but a smart one: a two-player hot-seat match still has surprising bite today.
Do not expect anything more: no weapon shops, no tournaments, austere character graphics. Yet here, in raw form, is the foundation that Scorched Earth and Worms would later build upon, and both as a history lesson and as a quick match for two, Artillery holds up.
You can fire it up directly in your browser on oldgame.cz, nothing to install.