... the players enjoyed getting to roll their AC on enemy turns instead of just passively taking damage when dictated by DM attack rolls.
This last is, by the by, one of the two reasons though I'm not hostile to player-facing game design, I'm not particularly a partisan of it; when dealing with NPC I don't want to "just decide" in at least some PC-relevant (but not PC interactive) cases.
Fair. Not all games are for all people.
I, personally, don't have that issue - I think I decide just as much when I am putting together a D&D encounter, or an encounter for a player-facing game. I choose how tough it is going to be either way.
It doesn't need to, since for all other things, D&D 3 doesn't dictate opposed rolls, but instead DCs set by the GM.But that's for a simple attack roll. It doesn't generalize to enemy actions broadly.
Wrong. In DL5A, essentially everything is opposed - the NPCs scores assume an average card, so that the players' card + attribute determines success/failure. Same with unisystem lite. The GM makes no rolls, only decisions. But they adhere to a more traditional mechanical approach (admittedly using cards instead of dice in DL5A, which is a bit non-traditional). BTVS is every bit as player facing as AW... but has a very different approach to the GM's roll. The GM makes no rolls, only decisions. And D&D 3 can be run that way. Just treat everything as opposed rolls with the NPCs rolls being take 10.The point is no-GM-roll (or "player facing", to use that term) games typically don't shift GM rolls to players - they eliminate those rolls entirely. Instead of rolling, the GM basically sets the stakes, and the players choose how to handle them.
Not always by the GM; a number of player facing systems make extensive use of random tables, but they're older and little known - such as the whole catalog from Better Games, especially Crimson Cutlass where a card flip is the determinant of the next scene/challenge, and the dice are to determine success/failure, with the GM being the narrator, not the adventure writer.In effect, in these games, the GM elements are not random. They are chosen.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.