C - FOCAL example 9 Lunar Lander Game.
Erase All,

01.01	X FOCAL(1,1)+FOCAL(3,3)+FOCAL(2,1)
01.04	T !,"CONTROL CALLING LUNAR MODULE....EMERGENCY ..."
01.05	T !,"MANUAL CONTROL IS NECESSARY.",!
01.06	T !,"YOU MAY RESET FUEL RATE K TO 0, OR ANY VALUE FROM"
01.07	T !,"8 TO 200 LBS/SEC AT 10 SECOND INTERVALS."
01.08	T !,"A NEGATIVE VALUE ABORTS THE LANDING."
01.10	T !!,"YOUR ESTIMATED FUEL RESERVE IS 16000 LBS"!
01.12	T !,"FREE FALL IMPACT TIME = 120 SEC. CAPSULE WT. 32500 LBS."
01.14	T !,"WE ARE TURNING ON YOUR RADAR....GOOD LUCK ! ",!!
01.16	S Q=1
01.20	T !,"FIRST RADAR CHECK COMING UP ",!!!
01.30	T !,"COMMENCE LANDING PROCEDURE",!
01.31	T !,"   TIME        HEIGHT            SPEED"
01.32	T "        FUEL      FUEL RATE",!
01.33	T "  SECONDS   MILES   FEET          MPH"
01.34	T "          LBS       LBS/SEC"
01.50	T !!

02.05	S L=0;S A=120;S V=1;S M=33000;S N=17000;S G=.001;S Z=1.8
02.10	T %6,L,%8,FITR(A),%7,5280*(A-FITR(A))
02.20	T %13.02,3600*V,%11.01,M-N,"     K=";A K;S T=10
02.70	T %7.02,;I (K) 2.74;I (200-K) 2.72; I (K-8) 2.71,3.1,3.1
02.71	I (K) 2.74,3.1,2.72
02.72	T !,"NOT POSSIBLE ";F X=1,51;T "."
02.73	T "K= ";A K; G 2.7
02.74	T !!,"LANDING ABORTED - CHICKEN!"!!!;Q

03.10	I ((M-N)-.001) 4.1;I (T-.001) 2.1;S S=T
03.40	I ((N+S*K)-M)  3.5,3.5;S S=(M-N)/K
03.50	D 9;I (I) 7.1,7.1;I (V) 3.8,3.8;I (J) 8.1
03.80	D 6;G 3.1

04.10	T "FUEL OUT AT ",L," SECS.",!
04.40	S S=(-V+FSQT(V*V+2*A*G))/G;S V=V+G*S;S L=L+S

05.10	T "ON MOON AT ",L," SECS.",!;S W=3600*V
05.20	T "IMPACT VELOCITY OF ",W," M.P.H. ",!,"FUEL LEFT: "
05.30	T M-N, " LBS.",!; I (-W+1) 5.5,5.5
05.40	T "PERFECT LANDING ! - (LUCKY ?) ",!;G 5.9
05.50	I (-W+10) 5.6,5.6;T "GOOD LANDING - (COULD BE IMPROVED ) ",!;G 5.9
05.60	I (-W+25) 5.7,5.7;T "CONGRATULATIONS ON A POOR LANDING",!;G 5.9
05.70	I (-W+60) 5.8,5.8;T "CRAFT DAMAGED - GOOD LUCK ",!;G 5.9
05.80	T "SORRY, BUT THERE WERE NO SURVIVORS - YOU BLEW IT ",!
05.82	T "IN FACT YOU CREATED A NEW LUNAR CRATER ",W*.277," FT. DEEP ",!
05.90	T !!,"CONTROL OUT ",!!;Q

06.10	S L=L+S;S T=T-S;S M=M-S*K;S A=I;S V=J

07.10	I (S-.005) 5.1;S S=2*A/(V+FSQT(V*V+2*A*(G-Z*K/M)))
07.30	D 9;D 6;G 7.1

08.10	S W=(1-M*G/(Z*K))/2;S S =M*V/(Z*K*(W+FSQT(W*W+V/Z)))+.05;D 9
08.30	I (I) 7.1,7.1;D 6; I (-J) 3.1,3.1; I (V) 3.1,3.1,8.1

09.10	S Q=S*K/M;S J=V+G*S+Z*(-Q-Q^2/2-Q^3/3-Q^4/4-Q^5/5)
09.40	S I =A-G*S*S/2-V*S+Z*S*(Q/2+Q^2/6+Q^3/12+Q^4/20+Q^5/30)

TYPE !"LUNAR LANDER GAME."!
TYPE !"THIS GAME ALLOWS YOU TO ATTEMPT A LUNAR LANDING SIMULATION"
TYPE !"BY ADJUSTING ROCKET POWER TO CUSHION THE LANDING."
TYPE !"START THE PROGRAM BY TYPING 'GO' FOLLOWED BY THE CR KEY."!!