Last week I posted two of the house rules I was going to use for my AD&D/OSRIC game. We played yesterday, and I'll have a full recap later. For now I want to talk about the house rules and how they went. In short, one of them worked so well that I can't imagine not using it. The other I never even used, because once we started playing I didn't care enough to bother with it.
Delta's Target 20 system was nearly flawless for use in combat. I'll use it whenever I play AD&D or OD&D. It kept things moving quickly, especially once I had the player's ACs memorized.
The really nice thing is that it kept questions and downtime to a minimum. When a character attacked, I reminded the player of the target's AC and that was it. After that it was die roll, and either an immediate damage roll or an announced miss.
There were plenty of times when I didn't even bother with the math. If the die came up a 17 or higher, I knew it was a hit. I didn't ask if the players had the same experience, but I suspect they did. We were moving through combat rounds at a breakneck pace.
In contrast, I didn't bother with the initiative rules. At least, not yet. I think there was a grand total of one spell cast in combat (bless, by Rob's half-orc fighter/cleric), and the initiative system really focuses on spells and keeping casters on their toes. With that insight in mind, I might tinker with it a little more and focus exclusively on casting.
Oddly enough, after years of running iterative initiative having everyone roll each round was fun and interesting. There were plenty of times, at least from behind the DM's screen, that initiative order was a big part of the tension. With things moving so quickly, I just had each player roll a d6 and act on that segment, starting with 1 and running simultaneous actions in the event of ties.
My experience with these house rules brought to mind an old essay by Vincent Baker. I'd link to it, but I can't for the life of me think of any terms that might bring it up on Google. In essence, Vincent argues that each rule a designer adds to a game should make the game more enjoyable. The best design is one that, if the players use all the rules, they have the most fun.
Obviously, that's a platonic ideal, but in play the two house rules showed that principle in action. Delta's rules made things move faster and let us get in more orc-bashing. My initiative rules would've brought the game to a halt and forced players to do math that had a dubious potential for making things more interesting. Thus, one rule lived, and one rule died.