Going from memory (I played that on a single 3 1/4" floppy, just to give a little perspective)…
Landscaping isn’t the only thing you’re capable of, but it is what you’ll be doing the vast majority of the time. Basically, you need flat land, and lots of it. In the early going, the best thing to do is to create at least one castle, then every so often raise the land nearby so it becoms a smaller settlement, releasing a settler. Do this until you have enough castles to ensure a steady flow of “mana” (indicated by one of the bars at the top of the screen. It can get frustrating in the early going because your walkers’ movements are COMPLETELY random, and they’ll very often completely ignore the best areas to settle. The only way to direct someone is to place your “papal magnet” (that big ankh thing) and use the “go to leader” command. This will bring people to the ankh and turn the first one that touches it into a leader, or bring the leader to it if you already have one.
As for your other abilities: Earthquake is best for lowering a high area quickly (especially good against volcanoes). It can kill people if water is deadly, but generally too random for this purpose, and it’s virtually useless if water is only dangerous. Knight turns your leader into a knight (they’re not generated automatically), which has tremendous destructive power and will destroy enemy settlements instead of just taking them over, effectively preventing other enemies from using the land. However, they drain you of a lot of population when they die, as well as deprive you of a leader; I recommend using them sparingly. Swamp creates several deadly patches of grond. If they’re bottomless, a well-placed swamp can wipe out literally dozens of foes. Shallow swamps are generally only good for killing enemy knights. Volcano creates a big area of uneven raised land with lots of rocks thrown in. Not really that effective for something that uses as much mana as it does. Flood lowers the entire world by one level; depending on the level, this may give you an outright victory or simply inconvenicence the enemy for a bit. Armageddon (which really isn’t as cool as it sounds) sends every person on the planet to the center (land will raise automatically if water is in the way) for one final series of battles for the planet.
Always note your opponents’ abilities. If all he has is the flood ability, keep everyone nice and high. If all he has is volcano, build either at sea level and have earthquakes handy, or build to the highest possible level (but this takes plenty of mana and makes it hard to build extensive settlements). And no matter what, DON’T STOP EXPANDING. For some reason, he can’t take over more than a third of the planet, so no matter how deep a hole you’re in, you’ll eventually come out on top so long as you avoid getting annihilated.
- Bonus! - How to beat level 999.
Stay at sea level so you don’t waste a lot of energy flattening land. Use the “settler eject” I mentioned earlier and expand as much as possible. He’ll send a knight your way pretty soon. If you have the mana for a swamp, swamp 'im (save in case you miss); otherwise, keep dunking him in water until he gives out. Do this for every other knight that comes by. For some reason, every enemy with the knight abilitiy will use it as much as possible; so long as you keep killing them, you need never fear any other retribution. When you have more than 1/3 of the planet, start bridging the gap to his territory and wipe his forces out at your leisure.
Damn, talk about a misspent youth…