In fairness, Wiz 1-3 were puzzle-heavy at the time, because they hid the mechanics. No internet then, and the manual gave only the vaguest hints as to how to obtain the ninja/lord classes. In fact, the mechanics for all classes were very much a 'work them out'. All you got in the manual was 'fighters are the best all-round front-line melee class, samurai are exceptional with swords and get some magic skills later, priests heal and can survive pretty well in melee, mages are glass canons, bishops will level slowly but access all skills, thieves are needed for locks/traps and might be good in combat if you can figure out how but we're not telling - and ninja/lord are flat-out the best, because lord gets all fighter advantages plus priest healing, while ninja gets a vague arrangement of auto-kills and special abilities that we won't elaborate on. We're also not telling you how you get those classes'.
Same applies for several of the more powerful spells - e.g. the description for the teleport spell is that it can take you into solid rock and perma-kill your whole party (very bad in a game where having a backup party to retrieve your main party to the temple for resurrection was a core mechanic) - even when you got the more advanced version that let you pick where to teleport, you needed to know the grid co-ordinates, which required flawless mapping. Same with all the resistances and protection-from-effect spells - you only had vague descriptions, so figuring out the actual mechanics of what effects what was the core point of the game.
The Wiz 1 dungeon is notoriously short, in that there's an elevator on level 3 that takes you straight to the last level if you want to go there. The game-time is in figuring out wtf each of the classes do, and how things work. Also, in the era of line-art graphics and hand-drawn mapping, those mirror/teleport/anti-light/anti-magic sections were not to be sneezed at puzzle-wise.
Well, in my book, a puzzle is something that can be solved with logic provided enough clues. If the only possible way to come up with a solution is through repeated trial-and-error, that's not a puzzle, just annoying busywork.
Trial and error was not a winnable tactic, due to the depletion of resources and deadliness of the traps. If your reaction to a level filled with squares that rotate you 180 degrees, or that teleport you, was to randomly wander, you'd lose your whole party
very quickly to pit traps. Again, that's different to a normal death, because you're not going to be able to send in your backup party to collect them and res, as they'll just die from the same mistake - it's a perma-wipe.
The way to win was to pay very careful attention to the mapping, and
stop as soon as something doesn't make sense. E.g. you can see that the corridor you're walking down should take 6 moves to reach the turnoff. You get there in 5. Something has happened, and you better stop, look around and try to work out
what has happened, because you can bet your ass that there's a nasty pit/teleport that's going to fuck you big-time if you just wander blindly.
Same with the spells, resistances and class abilities. You have vague descriptions to work with, but it isn't about trial and error - it's about paying attention. If you're watching what's going on, you'll notice that your samurai isn't hitting as hard as your fighter, but with a sword he's getting a progressively larger number of attacks per round - once you notice that, you can make use of it. Use logic - if flame spells work well on some undead monsters, they're probably going to work well on other undead. If you're fighting a bunch of noxious slimes, then spells that give sickness debuffs probably won't do much.
Another example - you'll encounter a ninja in a certain boss fight
much earlier than you'll get a character to access that class. Pay attention to what works well against it, and the ways in which it can carve up your party, and you'll have a headstart and how to make good use of the class when/if you finally access it.
