This repository contains the source code that allows patching Castlevania II: Belmont's Revenge to enable the following features:
- Improved Controls: allow the player to change direction in mid-air
- Subweapons: introduces all three subweapons (axe, holy water, and cross) into the US/EU rom.
There are two asm sources: patch.asm and patch-us.asm. The former provides only the air-control changes (but is compatible with EU/US, JP, and KGBC4EU roms), whereas the patch-us.asm provides both air-control changes and the three subweapons (however, it is only compatible with the EU/US rom.)
To build, run ./build.sh in bash. z80asm is required (Ubuntu: apt install z80asm).