Installation:
Put program SIMUL on your calculator. Voilą! Program FOURPLAY is only the source, so you don't need it (and if you don't know what a source is, you definitely don't need it).

Gameplay:
SIMUL can be run from Ion, MirageOS, DoorsCS, or from the homescreen by entering Asm(prgmSIMUL). A splash screen first appears. Use UP and DOWN to adjust the constrast so that the ugly pattern in the background is light enough that you can read the title but just dark enough to be annoying. Then set your speed. Press LEFT for Turtle (easy) mode, RIGHT for Ninja (hard) mode, or DEL for superhard mode. Press 2nd when done.

The GAME:
There are no instructions of any kind. Use your gaming instincts to beat Pong, Falldown, Keepitin, or Avoid. Lose one ball, and you lose the game. (Darn, did I just contradict myself?)

That's it?:
After six rounds, you get to Level II. In other words, you gotta play two games at once. Use MODE, ALPHA, X,T,?,n and STAT as the UP, LEFT, DOWN, and RIGHT arrow keys for the left-hand game, respectively (just like WASD on a computer keyboard).

Well...:
Try to get through the next eight levels. If you're lucky enough, you'll get to Level IV, or Fourplay, as I like to call it. Use 4, STO>, 1, and 2 for the third set of arrow keys, and 9, 5, 6, and - for the fourth.

Umm, any tips?:
Nope. I've never really gone too far in my own game, anyway. The easiest way to play Level IV, though, is to use your forefingers for the upper two games and your thumbs for the lower two.

Good luck:
You'll need it.