What this hack does is limit the variation of Hot/Cold bonus in the ROM. In the vanilla ROM, the Hot/Cold can vary between -9/+8 (negative is Cold, positive is Hot).   The RNG function used by many things in the game starts at 0x01107A. The RNG function requires an "input", and at the end, produces a "random" result using the "input" as its negative limit. For the Hot/Cold bonus, this "input" value is stored at 0x0F70AD. In the vanilla ROM, the value is 09.  Changing the byte at 0