As the two games are packaged as one, I can only start a new save. Which starts me in IV.

You can't start in V unless you find a way to separate the games, but you can go to V at any time by examining one of the pyramids. Note that the Darkside has some rather ridiculous quest rewards (500,000 experience just for answering a riddle) that could unbalance IV if solved early. Also, note that Castleview lets you train to higher levels than can be permanently reached in Clouds alone, which could also break game balance in Clouds.

On the other hand, if you do Darkside early, you might find those armadillo enemies to be quite dangerous. (Fortunately, they don't appear right away.)

But if I beat IV, will it send me directly to V? Or will it be one of those "You beat the game but can still explore" situations, in which I examine the pyramids them?

You can still explore after you beat IV, and can then examine the pyramids. Also, there is a pyramid in Castleview (the starting town on the Darkside) that you can use to get back to Clouds.

Note that triggering the ending will automatically save the game.

There is actually a special ending that you can only get after you beat both IV and V. Getting it requires traveling between the two worlds.

One more thing: The Dungeon of Death (found on Clouds, but the key is on the Darkside) is an advanced area. I recommend saving it for after you beat the rest of the combined game. (It's the one with the crossword.)

Thanks :3

MM V has infamous Armadillo road. So unless you don't mind using exploits, you pretty much need to do MM IV content first.

Oh and if you will try to avoid Amadillos' road, Killer Cobras in nearby forest are around 5 times worse.

Also if you start with MM5, you will be too strong for most of Clouds of Xeen, so it is better to play games in their respective order.

Okay :3

To be honest, "Oh and if you will try to avoid Amadillos' road, Killer Cobras in nearby forest are around 5 times worse"
I laughed at this, as it sounded almost like the game was trying to be satirical about how ridiculously dangerous fantasy worlds can be.

Armadillos are manageable if you use the spell that paralyzes beasts. They have a low index number, so the spell is very likely to work.

By the way, there is a special weapon you can only get in Clouds of Xeen. Hold on to it as it is unbreakable and ignores defense. (If you do lose it, there is a cheat to get another one.)

Where does "Swords of Xeen" fit into all this? I mean, it's not a numbered entry. So spin-off? But it plays exactly like a regular game so why not a numbered entry? Maybe it was a potential expansion that they decided to sell as it's own game instead?

Swords of Xeen, I believe, started out as a fan mod that New World Computing purchased and sold as its own game. Be aware that the game has a lot of bugs, so you will need to play defensively. This means you should save early and often and in multiple slots. Even if you're the sort of player who doesn't like to do so, still save early and often. Also, be aware that the game is poorly balanced, so you might want to play on the lower difficulty.

Of note, there is a fountain that will give you HP without limit. Be aware that getting over 32,767 HP will cause your HP to overflow and become negative.

One other thing about Swords of Xeen: Thievery is useless, so get rid of the Robber and Ninja in the starting party (yes, the starting party has both) and replace them with more useful characters. If you need Thievery, you can just buy the skill once you reach a certain point.

Basically, if you haven't finished MM4, the only place you should consider visiting in MM5 is the starting town. If you leave the starting town, you'll run into Armadillo road which is tough unless you rely on the paralysis spell. But the starting town in MM5 isn't too bad... characters starting in MM5 begin at level 5 though, so don't go there when you're still at level 1 or you'll have a hard time.

Having said that, even the starting town in MM5 will provide A LOT of experience, and will make you overpowered for MM4. So it's best to just stick to MM4 before venturing to Darkside. Later in the game, there will be more reasons to switch between the two which is cool.

You can start on V by renaming XEEN.CC to something else and then launching the game. It will start as Darkside (V) only. Start a new game - Save - Exit. Replace XEEN.CC. It will now be back to World.

Is there an equivalent hack for IV-only -- if anyone was so-inclined?

I'm not sure, but if you simply never travel to Darkside, then it's the same as playing IV only. The only difference would be the game's title screen I think.

There is also 100% EXP bonus until Lv15 in World of Xeen. Standalone MM IV didn't have that. Skills also could cost more in standalone MM IV - I am not really sure about this, but in WoX' Clouds when you try to learn some specific skills, you pay less than what trainer is asking from you (Pathfinding master in Vertigo is the most accessible example of this - just check amount of gold before and after you learn the skill).