Head On

Head On
Developer: Gremlin Publishers: Gremlin, Sega Platform: Arcade (Sega VIC Dual) Released internationally: April 1979 This game has uncompiled source code.

Head On is the first dot-collecting maze game, coming out over a year before Pac-Man. Of course, as you can see from the title screen, it's not much of a maze, and you run over the dots instead of eating them. Eleven years later, it got immortalized in the memory of every Sega arcade operator thanks to a downsized clone being stationed on every JAMMA board purchased, exploiting a loophole in Japanese laws that forbade developers from selling cabinets without any games.

Filler Text

There's filler text at the end of the game ROM. The text differs depending on the game version:

Head On (2 Player) (MAME: headon)	Head On (1 Player) (MAME: headon1)	Alpha Fighter / Head On (MAME: alphaho)
;MODS FOR 2 PLAYER ;8/31/79 ;9/5/79 ;9/6/79	;ERASE BONUS FBONUS: LD HL,PLAYER BIT 0,(HL) LD HL,153.341 JR Z,EBON1 LD HL,157.341 JR EBON1 EBONUS: LD HL,PLAYER BIT 0,(HL) LD HL,253.341 JR Z,EBON1 LD HL,257.341 EBON1: LD A,PBLANK LD BC,6.2 JP BOARD ;** ;PUT "BONUS" QBONUS: LD HL,PLAYER BIT 0,(HL) LD DE,13.13 JR Z,QBON1 LD DE,17.13 QBON1: PUSH DE LD BC,6 LD HL,BN1MES CALL PUTMES LD BC,6 POP DE INC D JP PUTMES PBONUS: LD HL,PLAYER BIT 0,(HL) LD DE,13.15 JR Z,PBON1	;** INIT: SUB A LD (LANCNT),A LD (DILANE),A LD (DICNTR),A LD (DIFLAG),A ;AR SIDEWAYS EV6: LD IX,CCTAB LD A,3 LD (TCAR),A LD A,(ADVERT) AND A JR NZ,EV6G ;CHANGE BITS TO DIR EXX LD E,(IX+JOY) LD B,4 LD C,0 EV6F: RR E CALL C,TSTDIR JR C,EV6E INC C DJNZ EV6F EV6E: LD (IX+JOY),C EXX EV6G: LD HL,SFT2 LD A,S1 ;** ALL CARS SIDEWAYS EV6C: EX AF,AF' LD A,EV5CLK LD (BC),A LD A,(IX+PAS) CP 2 RET C CALL SERV ;GET DIR LD A,(IX+JOY) CP 4 JR NC,EV6D LD C,A CP (IX+DIR) RET Z INC A INC A AND 3 CP (IX+DIR) RET Z ;SCREECH SOUND EX AF,AF' CALL SNDON ;MOVE SIDEWAYS ;C=DIR LD A,C CALL NEWDIR CA STACLE LD (IX+COL),0 CP HWALL JR Z,EV6A CP VWALL JR Z,EV6A CP PBLANK JR Z,EV6B ;OWN CAR? CP 15 JR NC,EV6H LD A,(TCAR) CP 3 JR NZ,EV6B EV6H: LD (IX+COL),1 EV6B: CALL UMOVE ;RESTORE FORWARD DIR EV6A: LD