WISH 95 question is (Internet Archive):
How many colors do you like in your gaming? Do you prefer four-color games? Or should game morality be black and white or shades of grey, and if the latter, how many? Are “evil” characters acceptable? Does your preference depend on genre? Do your preferences affect the genres you like?
I’ve got two answers for this — one for antagonists, the other for player characters.
When it comes to the opponents that players face, I prefer antagonists that run the entire spectrum of colors — a determined lawful good paladin who is at odds with the party can be as much of a challenge as a vile pit fiend from the Nine Hells. And heck, there’s always the bureaucracy to fight.
For example, a recent storyline in our Blackrazor campaign set in the World of Greyhawk involved the implementation of “Freesword Draft Act” being debated by the councils that rule our home city of Obsidian Bay. This act would have forced all non-guild aligned individuals into army service. Many of the characters in the campaign were for the act; others were against it, and each side mobilized their forces in order to get it passed or defeated. Each side had excellent arguments for and against, but the overall color was grey (which befits the setting perfectly).
I also prefer villains with complicated (and occasionally convoluted) plots that ensnare the good and wicked alike, and thus force the players to check their premises. I do like occasional foes that are absolutely evil — i.e. the Cult of Death Undying, which seeks to bring about a holocaust of undeath, or the vile Bloodlord of the Plains of Chaos, a demon who hungers for the blood of the Blackrazor Guild — but shades of gray offer more role-playing opportunities.
With player characters though, I’m less open-minded. I only allow characters along the neutral and good axis, with no evil or chaotic neutral characters. I’ve found both to be disruptive to the campaign, which itself tends to be more chaotic and good than anything else (although admittedly, many times chaos exceeds all other considerations).
That said, while I have no great desire for players to explore the depths of their own dark hearts at the gaming table, I have on occasion allowed evil characters. In these rare cases though, the player characters are working in tandem with me as extensions of NPC plots and schemes. No one sits down at the table and rolls up an evil character, but the possibility that they may turn to the dark side later on (or be replaced by a doppelganger, who does the turning for them) can never be ruled out. Some of the greatest moments in my campaign came from players who worked with me to betray their fellows, and I think DMs would be fools to deny themselves this tool.
Outside of Greyhawk, my approach to evil (and my tolerance for evil PCs) varies. For example, we do have the Realmsbreakers, an evil campaign set in the Forgotten Realms which is dedicated to the noble goal of the destruction of that campaign setting. However, it’s more of an over-the-top, evil overlord sort of evil campaign, rather than a dark and brutal one. Delta Green is a very dark setting in which players are often forced to choose between the lesser of two evils, knowing that either evil will lead to the destruction of their own souls, so yeah, I can easily see dark, tormented anti-heroes hunting the underbelly of America for the latest Mythos intrusion.
If I were to run a Mutants & Masterminds campaign I’d go with strictly four-color villains and heroes as befits its comic book setting, and with Stargate SG-1 I’m planning on having straight-forward villains and protagonists (though with a bit of subterfuge thrown into make things interesting).
I think that if you are going to allow openly evil characters in your campaign, or run an evil-only game, you need to talk with other players about their comfort level. This became readily apparent when we were preparing for the Realmsbreaker campaign, where we had some players who didn’t mind a Reservoir Dogs or Pulp Fiction level of evil, but drew the line with having demon-worshipers and diabolists as PCs. Even now, after having talked out what people were comfortable with, I don’t know if that campaign will really fly simply because the consensus on “what’s acceptable” is so nebulous.