NEW_LIFE starts every life, the first of a game included: it copies the two start records over the robot's and takes a life with DEC (HL) at $CA18, going to the game over (GAME_ENDED) when that leaves less than none. Make the DEC a NOP and LIVES never moves. The JP M after it still tests the sign flag, which both ways in leave clear (read: RESET_ROOM_COLOURS ends on a subtraction that leaves a small positive number, and the main loop's check on the robot's records ends on a zero). Put in before a game starts, the panel should show 05 instead of 04 (read). Tested: standing still in room $5E at U 96, V 160, where the chaser homes in (the room entered by the game's own restart), he was killed every 37 turns, and from 4 lives the fifth death, 170 turns in, was the game over. With the poke he died 33 times in 1200 turns and LIVES never moved.

POKE 51736,0

Whatever kills the robot does it the same way: the collision code sets bit 6 of the +$0D of the record it meets -- from the mover's bit 7, or the obstacle's bit 5 (ADJ_DU_FOR_OBJ_INTERSECT, ADJ_DV_FOR_OBJ_INTERSECT, ADJ_DZ_FOR_OBJ_INTERSECT) -- and the next time the legs' update routine (PLAYER_LEGS) or the top's (TOP_FOLLOWS_LEGS) runs, it tests that bit and starts the dying sparkle, marking the other half killed too. Make each BIT 6 a RES 6 -- one byte, the fourth of the instruction -- and each JR Z after it a JR, and the mark is wiped and ignored every turn, on both halves. (The legs' routine while he turns, TURNING_LEGS, never looks at the bit; the top's catches it then.) Tested: the same trial as the lives poke -- room $5E, standing still in the chaser's way -- five deaths in 170 turns and the game over without it; with it, 1200 turns, no death, and 4 lives.

POKE 49348,182: POKE 49349,24: POKE 50922,182: POKE 50923,24

RUN_CLOCK counts the light years down once a turn: CLOCK_BORROW takes one off the last digit (borrowing up the others) whenever the last digit has finished rolling into place, and all four at nought ends the game. A RET as CLOCK_BORROW's first instruction and nothing is ever taken off; the digits that are rolling finish their roll and stop. Tested: from the first turns of a game, 700 turns took the clock from 5997 to 5897 -- a light year every seven turns -- and with the poke it stayed at 5997. With the clock staged at 0001 at the start of a turn, the game was over 6 turns later; with the poke, 300 turns later it still said 0001.

POKE 44489,201

A valve (LOOSE_VALVE) steers itself to a chamber's socket, and activates the chamber when it sits on it, only when the socket is of its own kind: the JR NZ at $AF90 skips everything if the kinds differ, and the JR Z at $AFEF checks them again before the valve is seated (otherwise it would be destroyed, which never happens as the game is). Give the first JR a displacement of 0, so that it goes on whichever way the test comes out, and make the second a JR, and any valve does for any chamber. It becomes the seated valve of its own kind, which the summary counts all the same (SUMMARISE_CHAMBERS looks only for a seated valve in the chamber's room). Tested: in chamber $0C, whose socket takes kind 0, a valve of kind 1 put in the room's middle, high up, before the room was entered: without the poke it fell onto the things hanging in the middle of the room and lay there for 200 turns, and held over the socket and dropped onto it, it sat there another 200 turns with the count at 00. With the poke it steered itself onto the socket while the robot was still appearing, the room turned white and the count went to 01.

POKE 44945,0: POKE 45039,24

When a chamber is activated LOOSE_VALVE adds one to CHAMBERS in BCD and compares it with $24 at $B040: the twenty-fourth sets WON and ends the game. Make the CP $24 a CP 1 and the first chamber ends it -- a quick way to see the arrival screen, the rating for a finished game and the scene of the robot being oiled. Tested: a valve of kind 0 put in chamber $0C's room: without the poke it steered itself onto the socket, the count went to 01 and the game went on for another 100 turns; with it, WON was set and the game went straight to its end (GAME_ENDED).

POKE 45121,1

The things hanging from the ceiling (graphic 73, CEILING_DROP) fall one at a time on a turn when the random number is under 16 -- but only when DROP_LATCH is clear, and ENTER_ROOM sets it on entering an even-numbered room, where all four rooms that have them are ($0C, $1C, $58, $84); picking something up or taking an extra life there clears it. Make the RET NZ that obeys the latch a RET and they never fall. They are still deadly to walk into (read). Tested: in room $58, with its sixteen hanging over a floor of blocks, the robot stood on the block under one, and the latch was cleared as a pick-up clears it (the immunity poke in both trials, so that nothing restarted the room): without this poke all sixteen had fallen within 300 turns, one at a time, the last the one over him, which came to rest on his head; with it, none fell in 600 turns.

POKE 44317,201

A quarter turn costs a walking robot three turns standing still where two were meant (see the bugs): the sound TURNING_LEGS makes as a turn ends leaves C at nought, and C was the controls. These pokes put a four-instruction routine -- PUSH BC, CALL the sound, POP BC, RET -- into the first bytes of FACE_BY_STEP_UNUSED, code that nothing reaches, and call it in place of the sound, so the step meant for the last turn of a turn is taken. Tested: walking with A held and turning with Z (or X) for one turn in room $2B, U and V stood still for three turns without the pokes, and for two with them, after which the robot walked on 3 units a turn either way.

POKE 43807,197: POKE 43808,205: POKE 43809,212: POKE 43810,182: POKE 43811,193: POKE 43812,201: POKE 49688,31: POKE 49689,171

READ_KEYS sends the half-row it is about to read to port $FD before reading port $FE, an OUT that does nothing on a 48K Spectrum and pages memory on a 128K (see the bugs). The IN after it selects the half-rows by itself, so the OUT can simply go: two NOPs. Tested on the emulator's 128K machine, from the loaded game put into a 128K snapshot with the 48 BASIC ROM and bank 0 paged in and paging unlocked, as the 128's Tape Loader leaves it: without the poke the game crashed on its first turn of play; with it, 300 turns of play, walking out of start room $13 into room $14, and the paging was as it started. On the 48K the same 300 turns went exactly as without the poke, to the same room and the same spot.

POKE 46937,0: POKE 46938,0