Leaderboard

A simple game fully in Basic. This is a very little game I wrote on the commodore 64 ages ago, I changed it a little to work with vpeek, vpoke, the new color command, and the new screen resolution. To me starting with a simple game in basic is how I learned about the c64, and now the X16, before jumping in machine language. In the code for this game you can see practical examples, on how to set characters on the screen, read characters from the screen, change colors for characters, listen to the keyboard, set a screen mode. What surprised me was that I needed a delay in the code in order to have it not run too fast. This was not the case on the c64. I really like the way you can use the emulator in the browser, as it allows you to type in basic inside the browser, using "regular key mappings", and the run it. When I wanted to save it, I copy-pasted it into the installed emulator (hats off for who added he paste function there), and types the save command. This was done, because in the browser you cannot save it, and see it on disk (as far as I know) I added many REMs in the code, in order so it can be understood, and it is more of a tutorial, then a "real" game. Below I will go through the code. From line 5, the program initializes From line 9, the title screen is drawn From line 49, the game is initialized From line 199, the game loop starts From line 300, the game over screen is drawn Some miscelanious notes: The SCREEN command is used to set the screen in text mode (Petscii) 40x30 The color command is used to set character fore and background colors. Unlike the c64 each char has its own background color. There is no "global" background color CHR$(113) is used to draw the Petscii circle character, used on the title screen. Adding the actual character into the code listing, makes it hard to edit outside the emulator. CHR$(119) is another Petscii character VPOKE 0,0,x, pokes a character on the top level corner of the screen. So the text screen address = 0 (not like on the C64) On line 52 the bottom of the screen offset is calulated. NOTE: Even though the screen is 40 chars long, to get to VPOKE address of the next line, you need to add 256 bytes. SI and PI (StoneImage and PlayerImage) are Petsci chars, that are used in the game. NOTE: Petscii chars have different values in the PRINT or the VPOKE commands. Reminder: In C64/Microsoft basic a variable name is only two characters long max. Reminder: Lines in Basic should not be longer then 80 chars. When you make them longer, the emulator ignores them. A good place to see all PETSCII character codes is here: https://www.commanderx16.com/forum/index.php?/files/file/23-vera-chars/ Have fun! And the code itself: (it is easier to copy paste it in the browsers emulator and be able to modify it more easy here: https://www.commanderx16.com/emulator/x16emu.html ----- code below for copy past----- 5 REM SET TO 40X30 CHARS SCREEN 6 SCREEN 0 7 HM$=CHR$(19) 9 REM TITLE SCREEN ----------------- 10 REM SET COLORS TO BLACK AND WHITE, CLEAR SCREEN 11 COLOR 1,0: CLS 12 PRINT:PRINT:PRINT:PRINT : REM PRINT TITLE 13 PRINT " FALLING SNAKE": PRINT: COLOR 15 14 PRINT " YOU ARE FALLING DOWN A HOLE" 15 PRINT " AVOID ALL OBSTACLES" 16 COLOR 7: PRINT " PRESS SPACE TO START" 17 BA$=CHR$(113):BB$=CHR$(119) : REM BALL SYMBOLS 18 COLOR 2,0 : PRINT " "+BA$ 19 PRINT " "+BA$:PRINT " "+BA$ 20 PRINT " "+BA$+BA$+BA$+BA$+BA$+BA$+BA$+BA$+BA$;:COLOR 8:PRINT BB$ 25 GET A$: IF A$="" GOTO 25 : REM WAIT FOR KEY 35 TS=0 : REM SET TOP SCORE 49 REM START GAME ----------------- 50 COLOR 1,0: CLS 51 FOR T=1TO29:PRINT:NEXT 52 BO=29*256:SI=42: : REM BOTTOMSCREENOFFSET, STONEIMAGE 53 PO=15*256:PI=81:PC=2:PX=20 : REM PLAYEROFFSET, PLAYERIMAGE, PLAYERCOLOR 54 DE=1000 : REM DELAY VALUE 55 S=0 : REM SET SCORE 199 REM GAME LOOP ----------------- 200 GET A$ 201 IF A$=CHR$(29) AND PX<40 THEN PX=PX+1 : REM GO RIGHT 202 IF A$=CHR$(157) AND PX>0 THEN PX=PX-1: REM GO LEFT 210 X=INT(RND(1)*40)*2: C=INT(RND(1)*15)+1 : REM GET RANDOM STONE POSITION 211 PE=VPEEK( 0, PO+(PX*2)) 212 IF PE=SI THEN GOTO 400 220 VPOKE 0, BO+X, SI: VPOKE 0, BO+X+1, C 221 VPOKE 0, PO+(PX*2), PI: VPOKE 0, PO+(PX*2)+1, PC 296 FOR W=1 TO DE: NEXT : REM DELAY, SLOW DOWN CODE 297 PRINT : S=S+1 : DE=DE-1 : IF DE<0 THEN DE=0 298 GOTO 200 399 REM GAME OVER ----------------- 400 IF S>TS THEN TS=S 401 PRINT HM$:PRINT:PRINT:PRINT " GAME OVER": PRINT 402 PRINT " SCORE: "+STR$(S); 405 PRINT " TOP SCORE="+STR$(TS) 410 COLOR 7: PRINT: PRINT " PRESS SPACE TRY AGAIN" : PRINT:PRINT 420 GET A$ 421 IF A$ = "" OR A$=CHR$(29) OR A$=CHR$(157) THEN GOTO 420 422 GOTO 50