Cheats are very important from a debugging standpoint. I am also a particular fan of some of the ways old-school games let you cheat, and wish to bring back some of the magic.
Oddly enough, one of the most important cheats is already built right into the main game: the IT Guy in the village. Since he will give you free experience points if you give him money, all thats needed now is an infinite money cheat in order to get an infinite XP cheat.
What I'd like to do is include a "cheat room" inside the castle. This is not meant for players to find, this is not a secret to unlock, this is just a ridiculously well-hidden chamber where all of the cheating implements are available. The room will include a purse of infinite money and a number of high-level items, including everything you need to upgrade the starting armor. This should be everything we need to go from new game to whacking the end boss inside of 20 minutes. Just for reference, this room should also include a complete subway map.
Well we're also going to need at least these:
God Mode Fly No Clipping
We'll work out how to add that later.