Here are a couple codes I searched out while playing Optmon's Castlevania - The Holy Relics. There are a couple things in the game that are exclusive to it and I wanted to get those things exploited. So here you go.

Infinite Item Crash - 00DB?00:01

Open Doors Without A Key - 00DF:01

Vrad Manor Unlocked With All Relics - 00DE:1F