Ah, the music you get to hear when you start playing is music from Castlevania 2 for the NES, if anyone remembers it.. nice...
This D-Mod relies heavily on fighting, try to level up as much as you can (try to advance two levels before you enter cave, it's possible with one advencement too though, or even one). There is one house where you can get more health by killing the monster in the basement (the house with the duck), talk to the man first though. There is also another house north-west, above the dungeon, where you can find a strenght potion. You can refill you lives in the church for 25 gold pieces. Check out the house if you want to know more about the plot and go to the dungeon (west of the houses, down the stairs).
One down and you can choose between left, down and right. Go left for a golden heart (after some battles) and then right (no need to go down yet). More monsers here. Right again, up and right for a super potion, I would recommend that. Then back left, down twice, right twice, down twice and left. You'll see a female knight here, she'll give you an idol to pass the invisible walls (you would have seen them if you went down at the crossroads) .. Back right, up twice, left twice, down. Keep going left now, through the transparant wall. Eventually you'll end up in a room with the idol, get it, kill the monsters and get out. You'll be transported back to the female knight, she'll revive her friend and Martridge will teleport them away. Now go up a few times (4 or 5) and go left, a merchant will sell you a longsword here. Get out of the dungeon now, nothing more to do here.
Go the house with the guy that made a castle model, there's a note now saying he's gone south. Exit the house and follow the road south, you can pass now. The guard isn't a problem, go more down, and finally you get the chance to save again, I would do so, if I were you ;) Go down and right, look at the rock, now go down and two times left. Enter the house, Ash the woman about the rock, she'll open up a passage for you.
You're in the underground Cast camp now. Go down and search the guard for a level one pass. Up and two rights, go up here (you need the level 1 pass for this) and Farren will give you the level 2 pass. One down and 4 left, go up now (level 2 pass needed). Read the sign, search the chair, you'll get a password. Go down and keep going down, talk to the guard, he'll give you another password. Go all the way op, then right, passing the level 1 area, down till you get to another guard, tell him the password and you'll get the level 3 pass. All the way left again now, you can use the level 3 pass here. Read the sign for an epitaph looking a lot like another epitaph someone used in a d-mod :P You'll also find the level 4 pass. All the way right now, use the level 4 pass and you'll get into the store room. There's a super potion and an ID here, take both. Now keep going down and left, there's an area you couldn't access before, you can with the ID now. Save here and go down to find out what the Cast is up to (and try not to be annoyed by the blind cast members who will never see Dink wherever he hides). Dink will go up after the cut-scene, go back down and keep going till you see some cast members, move cut-scene follows.
Eventually you will have to kill someone, I won't tell you who, but talk to the king after that person is dead and the d-mod is over.