I've playing for RPG since 1984. Yes, it is a loooooong time. As the majority of long playing gamers, I played D&D, AD&D, 3rdD&D and hated 4th D&D. I have spend a lot of time playing around and have learn a lot of human nature and desires playing role playing games. But there were a bunch of things that kept me away from calling d20 rules as the perfect ones for role playing.
Codex Martialis resolves one of the most persistant demanding I had as a role-player: realistic but interesting combat. No, you are not going to find a lot of new spells, items, unnatural feats in this book. You would find an interesting, simple and realistic combat system. Let me share a story:
I've brought this book several months ago. I get so excited that I've begun to prepare a new campaign with my roleplaying game group. Al of them started used lvl 3 characters, in a low magic enviroment, using the wonderful Black Company magic system, with a great emphasis in role playing above hacking and slashing.
One of the PC was the town guard captain; a hardened veteran that have seen lots of fights. The traveling group was assaulted by a gang of kobolds. Kobolds!! Yes, you all konow them. 4hp, poor fighting capabilities, almost an amusement. The Guard's Captain said: "Don't worry. They are just kobolds".
No, man. Not using Codex Martialis rules. Now even kobolds have and edge in combat. Three of them really can take out a 3rd level character. As it happened. He died surprisingly quick by an attack of overconfidence. The hunter of the group saved the day using terrain and tactics in a very clever way. So I allways understood it is in real life.
That's something that Codex Martialis really mimicks very well. The author and contribuitors all know very well the fighting techniques of a contemporary ancient martial arts school. His effort to punt into d20 rules all the maneuvers, fighting and knowledge is really good.
First, Maneuvers. Here the author called them Martial Feats. Bad choice. It confused my players at the begining. I translate them to Trained Maneuvers and everithing went smoothly. Your PC will learn one Martial Feat (Trained Maneuver) per BAB point. There are several "branches" of Martial Feats that use combining maneuvers, all clearly worded and easy to imagine in movies and books. And even they are adding more and more with the help of contribuitors all around the world, emphasizing the regional and cultural difference. As in real life. You now can really have an "elf sword-fighting school", or a "high pass draven fighting style" or the "valley men fighting spear techniques".
Second, Combat. It is fast and lethal. They have came with a bright idea. Instead of getting a fixed number of movement and fighting actions in each round, characters have a dice martial pool. As you get levels, you gain d20 dice that you can use for several things. The number of dice you can have in this martial pool is recomended to be capped at 4, but you can cap it higher or lower depending of the epic and fantastic combat that you want. You can use each dice for moving, for changing weapon reach (onset, melee or close), keeping it for attacks of opportunity, using them for active defense (parring or blocking) or for focusing your attack (you can spend more than one d20 dice in your attack, keeping the highest roll). Simple but plentifull of tactical opportunities.
Third, Tools. No more you discard all the weapons but the scimitar or the long sword. Each weapon has his own set of simple numbers and maneuvers that makes you think how your character will fight. Lances has Armor Piercing capabilities and better reach, but unless you are trained properly, they fight poorly at closer ranges. Daggers, on the opposite, are lethal at close ranges, fast and easy to use against armor, but don't do a lot of damage. One of my PC used the tipical Sword and Shield fighting techniques, another has a 2 dagger close combat approach, and a third is a master of the quarterstaff. I could not say wich one is more lethal. They just simply use different approaches.
Armor, efectively function as a damage reduction, but you can try to bypass armor if it is hard to damage your opponent.
If you are looking for a more real approach to fighting still usind d20 rules, this is your book. If you try to simulate low magic enviroment fights, this is your system. If you thought how could you use a combat system like The Riddle of Steel in d20 games, this is your manual.
You have a great ammount of information in the www.codexmartialis.com web page, as how to use this system with monster or animals, how to develop new Martial Feats, and so on. I wish they could finish the 2.0 version prior this summer holidays. I have a lot of time to enjoy!
[5 of 5 Stars!]