Well now, I didn't mention it quite simply because I hadn't thought of it. I haven't been playing the game for a bit now. Ever since I went and bought Diablo II a few months ago, it's been practically the only computer game I've played. And my memory isn't some superhuman thing. I just gave the first example that popped into my head, and that was the Giant Growth thing. It strikes me as pretty bad. Sure, decision-making in a game like Magic might be tricky for an AI and I would expect them to be worse than humans even at this point, let alone in 1997. But for the AI to Giant Growth my creature when it has its own makes no sense. Even if the AI is bogged down with other details, the algorithms that tell it where to play Giant Growth could easily be written to exclude my creatures when it has its own creatures that could be targeted to no ill effect.
Anyway, I know pretty much nothing about programming, but I want to make it clear that I have never seen the AI pay mana to untap its mana vault. I'm not talking about us both doing lots of things on our turns and the AI doesn't know how to prioritize. I'm talking me playing Keeper and killing all the AI's creatures and emptying its hand and it has 12 lands out and is at 5 life with a tapped Mana Vault and it sits there taking Mana Vault damage until it dies. I couldn't program anything, I but I could easily come up with an algorithm that works better than never, ever untapping the Mana Vault.
And there were other issues. Most of them I remember weren't as bad as the Mana Vault one. For example, if you had Black Vise out, and the AI could play spells to get underneath the Black Vise, it would always do so, even if playing the spells was actually highly disadvantageous. I don't think it was getting confused by details. I think it was just sloppily designed and inadequately tested, which is really the same as the mountainwalk thing, even if that's rules and not decision-making. Both are "if x, then y."
Actually, maybe I'm off here, having never played MTGO, but I was under the impression that the rules worked properly there, so it seems rather laughable that they should not work in Duels of the Planeswalkers. Their work in implementing the rules should be essentially already done for them...
I mentioned Orgg's mountainwalk thing to Al0ysius, who has actually played Duel of the Planeswalkers (I have not). He noted there there are several annoying glitches in the game, which might explain the mountainwalk problem. A glitch interfering with the process sounds more likely to me than a total oversight in programming the rules interactions, but again, I don't really know anything. He also said that he's been able to exploit some glitch to take unlimited mulligans. Anyone know about this?