This past week I have started a new project. I have a board game pretty much finished and polished so the next step is obviously a roleplaying game like Dungeons and Dragons, only better of course! I dub it SkyRPG because I am terribly creative and good at naming things. A number of years ago myself and a bunch of my friends built a RPG together (though Sthenno went crazy and did 10 times as much work as anyone else) because we were really dissatisfied with the 3rd Edition D&D system. We had a wonderful system cooked up and were getting it nearly finished when out came 4th Edition D&D (hereafter known just as 4th) and we looked at all the great stuff they had done and basically shelved our project. We played 4th a bit and after giving it a run we discovered that the shine wore off pretty quickly and a lot of the great new ideas they had actually worked out to be mediocre or downright bad. 4th has been out for years now and I have not, up to this point, worked up the gumption to go for it and start again building my own game but now is the time.
The most fun part about building an RPG is coming up with all kinds of crazy ideas for spells and abilities. I love thinking of some new crazy thing a spell could do and then working out how to make it so that the numbers actually balance out. The hard part is coming up with basic mechanics that don't end up creating more problems down the road. For example, in 3rd a critical hit worked by multiplying the damage dealt of a weapon swing by 2, 3 or 4. This was *not* a good idea! Orcs were creatures appropriate for level 1 groups and the weapons they used did 1d12 + 3 with a critical of x3. It was entirely possible for a level 1 character with 5 hit points to be attacked by an 'appropriate monster' and be hit for 36! It got even worse as you levelled up a bit and were expected to fight dozens of orcs at a time since you could still easily eat a 36 damage attack and might only have 12 hit points to work with. Critical hits might be fun for the players when they get to annihilate a boss in one round but it isn't much fun when the GM has to fudge rolls to keep the party from blowing up before they get an action. 4th changed crits substantially such that you just do maximum damage instead of multiplying your damage by a large amount. Of course this means that on some attacks critting isn't a big deal at all and on some others it is quite important but either way I never much liked the fact that when I got a crit the damage total was always exactly the same.
My solution was to add damage on to the attack when a crit occurs. SkyRPG uses a system including the concept of Basic Damage which is used by various attacks and spells. Basic Damage roughly looks like:
Weapon Dice + Stat Modifier + misc. bonuses = Basic Damage.
Example of a Guardian wielding a Longsword, having a Might modifier of 2 and a magic weapon that adds 1d4 damage.
1d8 + 2 + 1d4 = Basic Damage.
This Guardian might use the ability Brutal Smash that knocks down the opponent and does 2 * Basic Damage. So this character would roll their attack and if it hit the opponent would be knocked down and take
(1d8 + 2 + 1d4) * 2
Critical hits operate by adding 1d8 damage to the character's Basic Damage on a crit. This means that crits scale with the power of the ability being used because more powerful abilities multiply Basic Damage. It also means that I have a pretty good handle on exactly how good a crit is and can easily tune it to be better or worse which is nice to have when I haven't written all the abilities yet. The ability above would do the following damage on a crit:
(1d8 + 2 + 1d4 + 1d8) * 2
It is a tricky balance to strike between letting players and monsters have truly hideous abilities that are fun and overpowered and trying to keep the campaign from coming to screeching halt due to unforeseen player death. The band that was going to save the world from OverDark Lord Omnapupa died to 4 orcs they randomly met while walking to the next town ... I guess evil wins after all.
If you want a link to what I have done so far here it is. Note that it is still *very* early and lots of definitions and basic things aren't there yet.