Is the earthquake spell at all useful? It just creates a chasm and I can't see it having any use, but maybe there are some situations where it is?

I think it has two or three uses.

1) It will do damage to any creatures caught in the aoe. So it is possible to kill things with it, though it never seemed very efficient to me. When I had other, more directed options, I generally preferred to use those options. Crater also does damage, and I think one level you had to use Crater (at least early on in the level) in order to kill anything. Both spells will hurt wizards flying on carpets; I have no idea why. I have used both to kill wizards though.

2) It does do some terraforming. If you're having trouble finding something, you can try dropping a few earthquakes to push things down to sea level. Occasionally this made it easier to grab a pot or something that was in a deep, steep hole.

3) If you have spare mana, it can be fun to "level" someone's castle with multiple earthquakes. You can get it down to just a flag. Of course, several seconds after you stop, the castle will just pop right back up again. This is amusement value only.

The spell sinks land into the water in a semi-jagged fissure, and I think it keeps running until it hits water. It will hurt any creatures on/above the land that is currently being affected (so wandering into the fissure after the active part of the spell has already gone past won't hurt). Maybe if you get creative, you can find uses for it beyond what I did.

FINISHED IT!!!

That level 49 was plain crazy. Got my ass handed to me on a plate several times, before I figured managed to do it. I almost cried after one time I killed the red wizard, reached level 7 castle and still lost after wyverns ganged on me. Got to be one of the hardest moments in gaming for me.
But once you finish it... what a feeling.
Once you got the global wave spell I knew I had it done. Several wyverns dying and dropping their mana at once is a magical sight.

Last level was easy in comparison, but a fitting finale. I enjoyed it.

The ending movie though, very disappointing...

The only level I found tedious (not difficult, but tedious), was level 43, the one where you start without a castle and must defeat all the kraken in the lake to get the castle spell with only a fireball and a genie on your back. Oh, and every now and then swarm of bees come your way. Boring repetitive and tedious.

On to Hidden Worlds!

Bookwyrm627, thanks for all your help. I was really close to giving up when I started. I owe you a beer.

Congratulations!

I thought about warning you about the wyvern level, but then decided "Nah, lets let it be a surprise." How did you beat it, btw? I'm pretty sure my method was sort of a glitch that screwed with the AI. I'd basically use the castle teleport spell every 3-4 seconds, and the wyverns didn't own me or my castle in the face. Then it was just a case of slowly wearing down whatever I could. Hardest part, after I found a workable strategy, was reminding myself "You've been here nearly 5 seconds. Get thee hence. No, don't do that thing, leave, NOW!" But this level is what really made me fall in love with Global Death.

Perhaps the most annoying level was the one where you have to enter the teleporter maze and clear a series of rooms with monster spawns in them. I remember making my way to the room where the wyvern spawns, and I was like "How the devil am I supposed to kill this thing without a castle or high level spells?" Next life, run past it, right into the waiting claws of a bunch of meteor crabs. I had to use a glitch to get a castle outside the maze area that was large enough to work with.

And the ending sequence. I don't remember being disappointed, probably because I was too shocked. It plays, drops me to desktop, and I'm left going "Wait, what?" It did feel a bit fitting to me, though.

I need to do Hidden Worlds too, actually. I played the first level once, many years ago, and then got distracted.

Well, initially I tried bulding my casle inland, away from the red wizard and the swarms, and get the mana from lesser creatures, but I couldn't get my castle above 4-5 before being destroyed.

Then I realized, you should not get the mana from the creatures. Instead you should get it from the red wizard. He has tons of it in his castle ready to be taken.

So my tactic was, grab the red wizard's attention (if he starts instead fighting with the purple one early on, try attacking his castle and see if he comes over to you). Build your castle close to his. Get the wyverns/griffins to attack his castle.

Getting the creatures to attack his castle is not easy, but not difficult either. The best thing that can happen is if (while attacking you for example), he hits a swarm of griffin, and they all gang on his castle. Wyverns help too.

Then soon it will be raining red balls. Get the red mana as fast as you can. A big help is if the red wizard dies while red mana is scattered around and you quickly claim his corpse getting all the mana. Though if you die you lose mana too.

Of course it's still very hectic, because the creatures will be attacking your castle too, so often you will just be there hoping you're quick enough in rebuilding it. It would be good to set up a teleport to the other side of red wizard castle where you can go if things become too hot. Once the red wizard is dead it becomes slightly easier.

Like I said, I once died in spite of having a level 7 castle and the red wizard dead. So don't be afraid of relocating. Go away. Destroy your castle Shift+L, and quickly build a new one (careful you don't die while without a castle).
You'll lose the ability to cast some spells (since they actually depend on amount of mana in castle, so it might be a good idea that once the creatures have left, you go back to the original site where all your mana is scattered and rebuild your castle there.

The purple wizard was just a minor nuisance. Once you get global death spell, the level is practically yours.

It took quite a few restarts with this tactic, but finally it worked.

Out of curiosity, did you ever try using a bunch of Undead Army castings to level a castle (in any level)? I found it works wonderfully well, since they don't cost anything after the initial investment, and in a large group they positively destroy castles of any size. Then a meteor on the army eliminates any threat they might have posed to you later.

Yes, used them a lot whenever they were available. Wonderful spell.
Of course it won't work in the levelv49 though, because you need to be well established before it becomes available (plus they're more effective on land castles). You had to get the wyverns/griffins to attack.

Finished Hidden Worlds. Not bad. No mission as tough as the wyvern one, and there are some where you start without the Castle spell, but none too annoying.

Muscle memory got so used to inverted y-axis that when I played an FPS I'd accidentally look up instead of down a few times...

Congrats! I haven't had the time to get into that one yet; still on my to-do list. But one day...