Dragon Quest (J) (Famicom version) has a glitch which might lead to a drastic improvement. I call it "Stones of Sunlight glitch".
(
cheap uploads
a demonstrating video (Japanese))
First, you can take chests unlimitedly if you fill up a "open-chest" array (address $2A, and it's capacity is 8 elements).
To do so, take some chests in a dungeon and die before you exit. Then the array is not re-initialized, so you can fill up the array before you take all chests in Tantegel castle.
(Note that the array always has 3 elements for the chest in the throne room in Tantegel castle)
In this situation, if you take the chest which contains "Stones of Sunlight", a glitch occurs and the game displays a string "12345".
It is harmless by itself. But if your inventory is full, the game corrupts the window buffer.
In this situation, the game causes a significant glitch if you do an action which scrolls the message window (e.g. dropping an item to take Stones of Sunlight, or using a cursed item).
In this glitch, the game reads the beginning of zeropage memory as text scripts. So, you can manipulate some bytes which is read by the game as text script bytes. For example, you can manipulate $47 (input), $4F (frame counter), or $94 (RNG state).
And, the game behaves more differently if you write "script commands" on memory. (e.g. script command 0xF7, 0xFA, 0xFC, 0xFE, 0xFF...)
I confirmed that the game executes some RAM addresses by this glitch. But in this game, you cannot manipulate so much RAM contents. So for now, I think it is very difficult to use this glitch to cause ACE.
And, I confirmed that the game sometimes writes 0x54 at address $E4 by this glitch. This means the "beat Dragonlord" flag (bit2 of $E4) is enabled. But immediately after, the game is softlocked.
(I put example movies for reference:
1,
2)
If you can avoid the softlock, you will be able to get to the ending immediately.
By the way, NES version doesn't have this bug.
The reason for this bug is that the game fails to initialize a string buffer when the open-chest array is full, but NES version doesn't have this problem.
