missile.icn: Program to play missile command game

Here is a cheap attempt at a Missile Command game.

I've run it under Icon V8.7 under VMS, Unix, and V8.5 under MS-DOS.

Here are some things you'll need to know. There is a delay() procedure
that keeps the game running at a steady pace. delay() is built into
V8.7 on VMS and unix. Under DOS you'll need to roll your own.
The program also uses ansi escape sequences. Also to play use 7, 8, and 9
to launch a # missile. 7 is leftward, 8 is straight, and 9 is right. A bug
in the Ultrix version (kbhit() and getch()) requires double pressing the
buttons. I think q will quit the game early.

Have Fun!