About
The README refers to Claim Jumper as "the classic game" for the Atari 400/800 home computers. ClaimJumper preserves the original 6502 assembly source code for the Atari 400/800 game Claim Jumper by Gray Chang, modified so it can be assembled with the 64Tass assembler instead of the original SynAssembler format.
How it differs from the original
The only stated difference from the original release is technical: the source has been adapted to compile with the 64Tass assembler rather than the original SynAssembler.