Re: Handling Combat in PbP
I've spent a long time looking for the perfect combat rules - and I'm still looking. Having said that, I think I have something pretty close now.
The main problem with combat in PbP is, as you say, the time each turn takes. What you need to do is reduce the number of dice rolls to a minimum.
For example, I don't bother with Initiative rolls - they'll probably add several days to your combat round... Often, the order of initiative is obvious from the scene - one PC is closer to a target than another, is more dextrous than another, etc. If you leave damage until everyone has had a turn, it doesn't make much difference anyhow.
I found that D&D, Gurps, and all the old tabletop rules are fun around a table, but are an absolute chore in PbP. I found I had to either houserule them beyond recognition, or find something else altogether. You cannot sensibly take a rule set designed for one medium and use it in another, slavishly play it 'as written', and expect it to work.
You need a rule set that avoids 'a roll for everything'. The rules must be simple and easy to administer, otherwise players and GM alike get lost in the complexity. It's easy to administer a five-roll-per-PC turn if you're sitting around a table looking at the dice and the rolls are made in five seconds, but if you have 8 players and 40 rolls spread over the best part of a week, there's no way you're going to remember who rolled what, and you'll be constantly scrolling up and down to re-read the posts.
Ideally, you want a rule set that uses one, or at most two rolls per turn, so you only have to wait for everyone to roll once, or perhaps twice, to resolve the combat. Even the most mechanistic players can get bored with a combat that stretches over several weeks, and if you have 'storytellers' in your game they're likely to walk after (or during) the first clash.
A battle map that is updated every turn can be useful if a combat scene is complex, but OTOH if a combat is complex, it's likely to be lengthy...
Better, perhaps, to have a simple area map and use your GM omnipotence to ensure that the combat isn't too complex to begin with - less work for you and less waiting for the players.
If you have large numbers of foes (orcs, mooks, or whatever), dictate that they act together en masse and their numbers are reflected in increased 'effective skill'. The amount of damage you do translates to the number of them you kill. That way, you don't have large numbers of rolls, or fights spread all over the map. If you only have two combatants, or two groups of combatants, you probably don't need to know where they are - they're just 'together'.
PbP is a simple medium. You need simple rules to use it. If you want blow by blow detail, you need to use a different medium - get a group of mates around your kitchen table or use a real-time VTT link. Anyone who expects PbP to feel like a FtF session is going to be disappointed. PbP is much better suited to rules-lite or outright storytelling, rather than in-depth combat resolution.
In PbP your golden rule is K.I.S.S.
IMHO, of course. :)