The reason HBO's production of "The Deadly Game" is so good, while all the other HBO adaptations of stage plays have been thuddingly awful, is that the director of "Deadly Game" refused to do it the way HBO wanted. He preferred to do it right, and did.

"Deadly Game," condensed from a 1960 James Yaffe play (based on Friedrich Duerrenmatt's novel "Trapp"), was taped in London, under the direction of television veteran George Schaefer, who really is one of the giants in the field. "Game" is a slight little thriller, but because of Schaefer's thoroughgoing professionalism, and a cast worth triple its weight in pound sterling, immensely pleasureable on television.

The play will be shown seven more times by HBO, including today at 5:30 p.m. and next Tuesday at 8 p.m. HBO has just over 9 million subscribers nationwide, about 65,000 of them in the Washington metropolitan area via the Marquee Television Network (38,910), Arlington's Metrocable system (16,865) and Alexandria Cablevision (11,500).

Talky, simple and rather obvious, the play is given both dignity and sprightliness by the performances: Robert Morley--grandness itself--Trevor Howard and Emlyn Williams as three old cronies retired from criminal law but still aching to see justice done, and swiftly, in their own little world. Into Morley's Swiss chalet tumbles a stranded American tourist (George Segal, engagingly chumpy), who has guilt written all over his entire being.

The three old friends use dinnertable charm to lure him into a mock trial that, it develops, they take very seriously. It's a delight to watch them encircle Segal, quibble among themselves, and take their misbegotten stand against the amorality that, as everyone who cares knows, has swept over most of human civilization (Alan Webb, who plays the group's official executioner, died shortly after the production was completed, so this witty performance was his last).

You may see right through this play yet profoundly relish Morley, from the bench, announcing "Mr. Prosecutor, I will deliver the admonition hyah" or Williams, the defense attorney, complaining, "Your honor, must the dignity of this court be compromised by the prosecutor's taste for smoking-room tittle-tattle?" With actors like this, wordiness actually becomes a virtue.

While the play may not be much more substantial than one of the better editions of "Alfred Hitchcock Presents," the care that went into the production elevates it to a high order of mischief; it's as pungently sippable as good brandy. And as Schaefer notes from his Hollywood office, "Half of the history of the British theater is on camera there."

But the reason it works so well as television is that it is television--not another of HBO's dreadfully half-baked photographed plays. HBO has insisted in the past that these plays be taped on a stage in front of an audience, an artistic decision comparable to ordering all the Rockettes to put on cellulite. It adds an obstacle between the viewer and the viewed. Camera positions are drastically limited, close-ups are few and the actors all stalk around braying out dialogue using stage projection.

Of course it's absurd, in the first place, for HBO to do new TV productions of plays that have already been satisfactorily made into movies ("Barefoot in the Park," "Plaza Suite," "Wait Until Dark"), but just plain stupid to do them with so little regard for the demands of television.

Schaefer, whose television career includes glory days as producer and director on the "Hallmark Hall of Fame," agrees that most HBO theater pieces are disasters. "They're just horrible, aren't they? They would have liked me to have done this one that way as well," he says. "I told them I would not do it in a theater. I wanted to do it in a studio and make it look like the best 'Hallmarks' and 'Playhouse 90s.'

"It was a fight all the way through. I was under great pressure to do it the wrong way."

Why should HBO want these things done the wrong way? "They told me they feel it makes the plays look different from the stuff the networks are doing," says Schaefer. "I howled when I heard that. The networks learned long ago that the audience doesn't like it that way. It doesn't work."

To placate HBO, Schaefer shot an open and close that make it look as though "Deadly Game" were taking place on a stage. The people you see filing into their seats before the curtain goes up, and applauding after it comes down, are extras, recruited as part of the ruse. The play was actually shot in a BBC studio (the BBC was co-producer with HBO) over a five-day period in May.

Schaefer says that just before the first transmission of the play earlier this month, someone at HBO added fake applause on the soundtrack when such actors as Segal make their first entrances. He's mad about that, but he's willing to chalk it up to imbecility.

HBO is by far the biggest and most successful pay-TV operation in the country and it's irritating to hear horror stories from producers about its apparently frequent fits of wrongheadedness (could it be HBO gets its executives from the same clone mine as the commercial networks?). These tales discourage those who still harbor hopes that cable will provide true alternatives to the mediocrity of regular old TV. It will never do that if the people in charge don't trust the artists more than they trust their charts and graphs and computers.

"I'm in disgrace for sticking to my guns, but I know I'm right," says Schaefer. "These people have everything their way, everything going for them, so why not take advantage of that and do the best of television, instead of saying the best of television might look like CBS or NBC, and so do it some other way? It makes no sense to me."

Schaefer is now preparing another cable play, "Answers," a collection of pre-"Golden Pond" one-acts by Ernest Thompson, with a cast that includes Eileen Brennan, Ned Beatty, Burgess Meredith, Patty McCormack and Sam Bottoms. This is for CBS Cable, which seems not as pigheaded as HBO but which, Schaefer says, is entertaining the idea of cutting 10 or 12 minutes out of the plays to accomodate commercials--instead of just letting the plays run past an allotted two-hour time slot.

There's no reason cable should submit itself to the same running-time tyrannies as commercial TV. Says Schaefer, "I'm screaming to them, 'No no no no no! That's what you've got cable for!' " The talented and ambitious folk fleeing commercial TV for cable should take heed; they're going to have to keep their screaming muscles in shape.