Sssnake!!! (October, 1986) tends to crash after about 10 minutes under certain conditions of play. If you're one of the people who has gotten the message "Error 13 at 571," you can fix the listing by substituting the following two lines.
MX 570 FS1=FS1-N*(FS1>N):IF FSl<>N THEN 575
MY 571 POKE VVD,PUR:FOR I=N TO 200:POKE VF,I:POKE VF,I+TN:POKE BLF,I:NEXT I:GOTO 2000