"The stakes," the technician said softly, "are high, aren't they? Your life against its. Must be exceptionally appealing to someone with the right kind of temperament."

"I think," Tinbane said, "I can get the catapult before it's in action."

"Maybe. Maybe not."

"I'm getting the ball closer to it each time."

The technician said, "For the catapult to work, it requires one of the steel balls; that's its load. You're making it increasingly likely that it'll acquire use of one of the balls. You're actually helping it." He added somberly, "In fact it can't function without you; the gameplayer is not only the enemy, he's also essential. Better quit, Tinbane. The thing is using you."

"I'll quit," Tinbane said, "when I've gotten the catapult."

"You're damn right you will. You'll be dead." He eyed Tinbane narrowly. "Possibly this is why the outspacers built it. To get back at us for our raids. This very likely is what it's for."

"Got another quarter?" Tinbane said.

In the middle of his tenth game a surprising, unexpected alteration in the machine's strategy manifested itself. All at once it ceased routing the steel balls entirely to one side, away from the replica village.

Watching, Tinbane saw the steel ball roll directly – for the first time – through the center. Straight toward the proportionally massive catapult.

Obviously the catapult had been completed.

"I outrank you, Tinbane," the lab technician said tautly. "And I'm ordering you to quit playing."

"Any order from you to me," Tinbane said, "has to be in writing and has to be approved by someone in the department at inspector level." But, reluctantly, he halted play. "I can get it," he said reflectively, "but not standing here. I have to be away, far enough back so that it can't pick me off." So it can't distinguish me and aim, he realized.

Already he had noted it swivel slightly. Through some lens-system it had detected him. Or possibly it was thermotropic, had sensed him by his body heat.

If the latter, then defensive action for him would be relatively simple: a resistance coil suspended at another locus. On the other hand it might be utilizing a cephalic index of some sort, recording all nearby brain-emanations. But the police lab would know that already.

"What's its tropism?" he asked.

The technician said, "That assembly hadn't been built up, at the time we inspected it. It's undoubtedly coming into existence now, in concert with the completion of the weapon."

Tinbane said thougtfully, "I hope it doesn't possess equipment to record a cephalic index." Because, he thought, if it did, storing the pattern would be no trouble at all. It could retain a memory of its adversary for use in the event of future encounters.

Something about that notion frightened him – over and above the immediate menace of the situation.

"I'll make a deal," the technician said. "You continue to operate it until it fires its initial shot at you. Then step aside and let us tear it down. We need to know its tropism; this may turn up again in a more complex fashion. You agree? You'll be taking a calculated risk, but I believe its initial shot will be aimed with the idea of use as feedback; it'll correct for a second shot… which will never take place."

Should he tell the technician his fear?

"What bothers me," he said, "is the possibility that it'll retain a specific memory of me. For future purposes."

"What future purposes? It'll be completely torn down. As soon as it fires."

Reluctantly, Tinbane said, "I think I'd better make the deal." I may already have gone too far, he thought. You may have been right.

The next steel ball missed the catapult by only a matter of a fraction of an inch. But what unnerved him was not the closeness; it was the quick, subtle attempt on the part of the catapult to snare the ball as it passed. A motion so rapid that he might easily have overlooked it.

"It wants the ball," the technician observed. "It wants you." He, too, had seen.

With hesitation, Tinbane touched the plunger which would release the next – and for him possibly the last – steel ball.

"Back out," the technician advised nervously. "Forget the deal; stop playing. We'll tear it down as it is."

"We need the tropism," Tinbane said. And depressed the plunger.

The steel ball, suddenly seeming to him huge and hard and heavy, rolled unhesitatingly into the waiting catapult; every contour of the machine's topography collaborated. The acquisition of the load took place before he even understood what had happened. He stood staring.

"Run!" The technician leaped back, bolted; crashing against Tinbane, he threw him bodily away from the machine.

With a clatter of broken glass the steel ball shot by Tinbane's right temple, bounced against the far wall of the lab, came to rest under a work table.

Silence.

After a time the technician said shakily, "It had plenty of velocity. Plenty of mass. Plenty of what it needed."

Haltingly, Tinbane stood up, took a step toward the machine.

"Don't release another ball," the technician said warningly.

Tinbane said, "I don't have to." He turned, then, sprinted away.

The machine had released the ball itself.

In the outer office, Tinbane sat smoking, seated across from Ted Donovan, the lab chief. The door to the lab had been shut, and every one of the several lab technicians had been bull-horned to safety. Beyond the closed door the lab was silent. Inert, Tinbane thought, and waiting.

He wondered if it was waiting for anyone, any human, any Terran, to come within reach. Or – just him.

The latter thought amused him even less than it had originally; even seated out here he felt himself cringe. A machine built on another world, sent to Terra empty of direction, merely capable of sorting among all its defensive possibilities until at last it stumbled onto the key. Randomness at work, through hundreds, even thousands of games… through person after person, player after player. Until at last it reached critical direction, and the last person to play it, also selected by the process of randomness, became welded to it in a contract of death. In this case, himself. Unfortunately.

Ted Donovan said, "We'll spear its power source from a distance; that shouldn't be hard. You go on home, forget about it. When we have its tropic circuit laid out we'll notify you. Unless of course it's late at night, in which case -"

"Notify me," Tinbane said, "whatever time it is. If you will." He did not have to explain; the lab chief understood.

"Obviously," Donovan said, "this construct is aimed at the police teams raiding the casinos. How they steered our robots onto it we don't of course know – yet. We may find that circuit, too." He picked up the already extant lab report, eyed it with hostility. "This was far too cursory, it would now appear. 'Just another outspacer gambling device.' The hell it is." He tossed the report away, disgusted.

"If that's what they had in mind," Tinbane said, "they got what they wanted; they got me completely." At least in terms of hooking him. Of snaring his attention. And his cooperation.

"You're a gambler; you've got the streak. But you didn't know it. Possibly it wouldn't have worked otherwise." Donovan added, "But it is interesting. A pinball machine that fights back. That gets fed up with steel balls rolling over it. I hope they don't build a skeet-shoot. This is bad enough."

"Dreamlike," Tinbane murmured.

"Pardon?"

"Not really real." But, he thought, it is real. He rose, then, to his feet. "I'll do what you say; I'll go on home to my conapt. You have the vidphone number." He felt tired and afraid.

"You look terrible," Donovan said, scrutinizing him. "It shouldn't get you to this extent; this is a relatively benign construct, isn't it? You have to attack it, to set it in motion. If left alone -"