On Friday night, Douglas Cole and I did a play-through of a fight using his excellent book, GURPS Martial Arts: Technical Grappling.
I read the book a couple of times - both in total and in pieces. I was in the playtest for the book, but at the time, I had a lot going on. I couldn't follow the playtest too closely, so much as lurk on it and pay attention when Doug needed a specific answer on things from the authors of GURPS Martial Arts.
And then, the book changed a bit during playtest, when it because clear that some ideas needed to change to accomplish what Doug was trying to accomplish.
Long story short - I needed to try the rules out in play, and it seemed like a good idea to try them out with the author since he's my friend.
Basically, TG changes grappling from simple, binary effects (grappled or not grappled, pinned or not pinned, break free or don't break free, locked or not locked) to an effect-based system. Grab, roll to see how well you've grabbed and how much control you've achieved. Try to escape, and roll to see how much "damage" you do the hold.
There are a little nuances to it, though, which means it's not quite so straightforward.
To call what we did a "fight" overstates it a bit. Doug whipped up a knife-armed strong thug, and I grabbed a BJJ fighter we'd cut from the main text and put into the Designer's Notes. We stopped a lot, considered tactics, discussed alternative moves and how they'd work, occasionally swapped in different stats for the opponent to see how that would work ("If this was a ST 20 SM+1 troll, then what?"), talked about real-world grappling and what it entails in the rules, and so on. But it was a good way to try the rules out and stop and ask when I didn't know why something worked the way it did.
The fight itself was pretty fun. Mostly "my" guy got in trouble when he got overly aggressive. A nice Judo Parry-Judo Throw without a hold worked, except the opponent wasn't stunned so he didn't drop his knife, and the lack of arm control meant that was a foolish thing to do (and lead to a luckily-weak cut to the arm). He'd have been better off achieving knife control and saving the throw for later, but my goal was to get entry and grappling rolls in, and establish how it would start, not "win."
Patience and Time - like in real grappling, or at least how I personally grapple, you need to be patient. While you can sometimes just grab, toss, and submit, without cinematic abilities you really do need to take some time. Grab, establish a solid (and possibly reinforced) hold, work for superior position, inflict submission/damage/incapacitation. You grab, you get some Control Points (CPs), accumulate enough to make it hard for the opponent to escape, then go for moves to finish the job. Very realistic - grappling is time-consuming compared to throwing a successful strike, which either hits or doesn't, finishes him or doesn't. Grappling can be much more involved, and a poor gambit can result in losing everything you worked for.
High Risk Is High Risk - a quickie grab-and-throw with Judo is good, and still works very well in TG, but doesn't give you much control. For my test fighter, the smart move would have been to throw the guy down and then just run - by the time Mr. Knife stood up, he'd have been yards away at stationary and my guy would have been gone. But as a fighting method, it ended up relying a bit too much on hope ("I hope he gets Stunned and drops his weapon!" - Nope.) Which is fine, of course, just worth noting.
There is a lot to digest - You need to know a lot. You do need to know your trained ST for multiple skills (you can't grab with Judo and roll with your Wrestling-modified ST, sadly). You need to know (or look up) your single-limbed grappling ST score. You need to have a solid idea of what the rules let you do and not do in order to either grapple or avoid grappling. Your size modifier, relative weight, and relative ST can change how the rules apply to you. So it didn't feel simple. Good, solid, and very much like real grappling, but not dead simple.
Recursive Math Sucks - TG has a great concept in "Referred Control." Basically, if I get your arm and your neck, my hold on the arm makes my control on the neck better and vice-versa. It also interferes with other moves involving your whole body. Because of this you end up with control of A+part of N on the arm, N+part of A on the neck, some bit of A and N on the torso, etc. For a detailed fight this is awesome, but I'll need a much better handle on it before I can use it in play, especially in my DF game. Doug and I talked about how to automate the process, and about some ideas for winging it (a simple one-calc penalty instead of a detailed calculated penalty). This is one of those areas where there is just a lot of work, even if what you get out of it is great stuff.
Grapple-Heavy Monsters Are Even Worse Than You Imagined - the DFM1 troll we tossed in to calculations once or twice was really nasty. A big grappler is bad already in GURPS if it gets its mitts on you. In TG, the effect-roll based control means it's going to really get a good hold on you and it's hard for you to really inconvenience it. Which is cool with me, because that means a grapple-and-bite threat can be even more serious in a game like DF. They're a threat now, but I like how TG allows for a range of danger beyond simply "grappled and in danger" and "not grappled and fine."
Overall - I liked the rules a lot. I think effect-based grappling is a good idea. Instead of a flat effect, binary, grappled-or-not grappled (-4 to DX), you grab and roll "damage" that gives you CP - control points. I really liked how much the results made sense - moves I could really do really work, and the patient, control-first martial arts style I learn (Kachin Bando) makes even more sense in play since piling on CPs is nothing but good. Now that I've got a better handle on the rules after a run-through, I feel a lot more comfortable with the rules set and I'm even more pleased to have them handy. I also like how it handles weapons, and I'm looking forward to trying that out with Doug next time.