Gary Gygax had a letter in the second issue of Alarums & Excursions. There is a version of it online at the Acaeum forums. I definitely have to recommend reading the whole thing, but I just want to put an extract on monsters that I think is very relevant.
Dave and I disagree on how to handle any number of things, and both of our campaigns differ from the "rules" found in D&D. If the time ever comes when all aspects of fantasy are covered and the vast majority of its players agree on how the game should be played, D&D will have become staid and boring indeed. Sorry, but I don't believe that there is anything desirable in having various campaigns playing similarly to one another. D&D is supposed to offer a challenge to the imagination and to do so in many ways. Perhaps the most important is in regard to what the probabilities of a given situation are. If players know what all of the monster parameters are, what can be expected in a given situation, exactly what will happen to them if they perform thus and so, most of the charm of the game is gone. Frankly, the reason I enjoy playing in Dave Arneson's campaign is that I do not know his treatments of monsters and suchlike, so I must keep thinking and reasoning in order to "survive".I have long had mixed feelings about this. I love monsters. You can't long have read this blog without noticing that. And I love bestiaries — whether it's the extremely "light" format of the Swords & Wizardry Monster Book, or the thoroughness of the AD&D 2nd Edition Monstrous Compendium and its many appendices and annuals. I could go to my shelves and populate a very large dungeon without repetition of a single monster.
My experience has been that unique enemies work best as contrast. This also corresponds to the "weirdness level" of the individual monsters: something that's familiar-ish but odd can then alternate with something really out-there. For instance, various types of beast-men are good substitutes for humanoids if you're bored of orcs, goblins and bandits. If you have a group of goat-men, then they provide a decent backdrop against which something full-bore odd, like a chimeric creature from Geoffrey McKinney's work, can stand out.
Lacking this element of contrast, monsters tend to become more or less similar. If everything is equally weird, nothing is really weird. Lamentations of the Flame Princess has an interesting solution to this dilemma: remove everything except for one big monster (which is really strange and unique), and make everything else humans or animals. But the "monster of the week" is a hyper-focused format, and doesn't fit if you want to do a megadungeon or hexcrawl full of interesting and diverse factions.
An alternate solution that I've been playing with works more or less like this:
- Strip back the bog standard monsters to the very basics: humans and animals (including, at most, some varieties of giant animal).
- Create new creatures similar to the default monsters for the intended level. Change appearances and special abilities, but keep HD / AC ranges similar.
- Make a few "big impact" monsters that are totally unique.
- Give the players ways to find out about the impact monsters' characteristics and abilities.
I'll have more tweaking on this method as I get to see more of its results in practice, but I'm liking the results so far.