There are two important considerations when beginning the design of a new campaign. One is as important as the other, and they are actually intertwined, so they both come first. They are Genre and Rules set .
Genre is far more than just the setting. Medieval fantasy, futuristic sci-fi, wild west, modern day action are all common RPG genres, but within that is actually the style of the game. Is your medieval fantasy all chivalrous knights and elegant wizards vying for power, or is it gritty dungeon delvers looking for fast treasure and enough magic firepower to turn armies to ashes. Could it be modern with super heroes or spies or ghost hunting secret agents. The style of the campaign is really a combination of what you want and what your players want. But that tone determines the best rules set to use. And there are a lot of choices.
For a moody atmospheric game that is more into character interaction, White Wolf created World of Darkness. It’s great for a game with super powered characters. The games that use it are based on PCs that are various supernatural creatures. The core rules now go under the title Chronicles of Darkness and available at Drive Through RPG (http://www.drivethrurpg.com/). Although, with some looking, you can probably find an earlier edition to download online.
The D6 System from West End games is a great system for games that require characters to be able to do a lot of things. Pulp hero style adventures, science fiction, that sort of thing. It was originally used, with 20 years of success, for the first Star Wars RPG. The rules can be downloaded for free at Whitesaber. (http://games.whitesaber.com/west-end-games-open-d6.html)
The Hero System was originally developed for a superhero RPG called Champions. It has been refined into a versatile set of rules, but it’s not free. In fact it’s a bit pricey,. The system is point based and fairly complex. But it is detailed. Great for campaign settings where every little detail counts. The Hero System is available at Hero Games, http://www.herogames.com/forums/store/category/2-hero-system-6th-edition
A great all around system is GURPS, the Generic Universal Role Playing System. It’s been around for a long time. It’s point based, and fairly detailed. It’s always been a very polarizing game system, players either love it or hate it, and there are few opinions in between. I’ve always liked it, and I love the huge amount of source material available for it. I often use the many source books for reference on all kinds of projects both in and out of the gaming field. But it’s point based. That means players often end up spending vast amounts of time optimizing characters. I’m really not the optimizing type. I like quirky characters that are full of surprises when played. But GURPS is certainly worth a close look. http://www.sjgames.com/gurps/
There are a whole lot of other systems out there that make great campaigns. The point here is, to weigh teach one carefully to see if it will promote the genre and style you want to focus on in your campaign.
I am actually going to combine two sets of rules for this campaign. I really like personalizing my game. In the good old days, every game was completely different, even though Dungeons and Dragons was the rules set everybody had. The rules were so loose and open to interpretation, that everyone used house rules. That is, those rules the players all agreed on for thigns that weren’t covered, like what actions could happen during a melee round, and how long a melee round actually was. And the original rules allowed for players to run pretty much anything as a player character, so if a player wanted to run a genie, it had to be designed as it’s own character class. When you went from one game to another, you never entirely knew what to expect. I’ve gotten very used to that. I’ll be using original Dungeons and Dragons and another game called Fringeworthy.
Old Dungeons and Dragons rules are pretty common these days. The original books; Men and Magic, Monsters and Treasure, and Wilderness Adventures, along with Greyhawk, Blackmoore and Eldritch Wizardry can be downloaded as PDFs on line. Drivethrough RPG is a good site to find these. Also, there are quite a few versions of the rules available as free, or very inexpensive downloads available under the Open Gaming License. My particular favorite is Swords and Wizardry. https://www.froggodgames.com/swords-wizardry-core-rules
There are a lot of things I like about the old Dungeons and Dragons rules. Flexibility is one. You can always add more to it. Plus it is a dice roll based character generation system that is very straight forward. There has always been criticism that dice roll based character creation isn’t fair – some players just get better dice rolls, and therefore have better characters. But I see it as being able to play the hand you are dealt, as they say in card games. And besides, a lot of the fun is in how you actually play the character, incompetent characters can be particularly fun.
The real core of this campaign is Fringeworthy. It’s a fairly obscure rules set originally published in 1982. Like most rules from that era, it is based on the mechanics of Dungeons and Dragons. This system adds a fairly comprehensive and complex skill system, and a combat system that has to be seen to be believed. It is complex and complete, with over 133 hit locations. But what I really like about this RPG is the setting. The game is about explorers investigating alternate realities. This system is worth owning. It’s one of the earliest multi genre settings and the company the produces it, TRI-TAC has a number of other amazing RPGs and board games as well. Very much worth checking out. http://tritacgames.com/index.htm
So, my genre is multiple genre characters all in the same high fantasy setting setting. My Rules set is a combination of Original Dungeons and Dragons and Fringeworthy.
Next up, we build the world.