I hadn't heard of this story before, but was intrigued by your question so I searched around a little and found that this question has been answered elsewhere. It appears to be "Catacomb" by Henry Melton from issue #97 of Dragon magazine May 1985.
He spoke. "I would appreciate it if you stayed right where you are!" She froze, her mind in high gear. He could have a nocked arrow aimed her way. If so, the aim would be hampered by the very rocks that protected him; no other weapon would have a better chance. He was either stupid or bluffing.
<DIVE INTO A ROLL. GRAB MY PACK. USE MY PACK AS A SHIELD . GET THE BOTTLE OF POISON> She felt the embossed bottle in her pack just as the stinging bite of a dart found her arm. Lunae fought for consciousness as a wave of buzzing darkness rushed over her.
YOU HAVE BEEN RENDERED UNCONSCIOUS ON A POISONED DART. YOU ARE L0GGED OFF CATACOMB FOR 00:30 MINIMUM. YOUR ACCOUNT BALANCE IS: $ 0.78 FOR TODAY $ 12.40 FOR THE GAME $ 7.50 TREASURE BONUS {RESERVED}
....
Lunae came to consciousness with the feel of her pack under her head as a pillow. Her thief had left her stretched out comfortably, concealed behind the rocks that had protected him. A quick survey of her pack and her person revealed only the ruby missing. Even her weapons were still in their places. She was puzzled. Most thieves would have left her dead and sold her provisions back to the Wizard of the Gate.
After she kills a "Tor beast", she acquires an armlet from it that is also of an undefined value.
Judith rapidly keyed the logoff and dashed out of her room, not waiting to view the message on the screen
YOUR ACCOUNT BALANCE IS:
$ 1.58 FOR TODAY $ 13.20 FOR THE GAME $ ??.?? TREASURE BONUS {RESERVED} {CONDITIONAL = 53}
The need to manually move her feet is actually from a later encounter with a "garbage collector".
<SMELL, LISTEN> The musty scent gagged her. If there were any scent of her thief, it was masked. She just stood there, engulfed by the odor. Something about it seemed to dull her reactions. To her right, from the direction she had come, she heard a scrapping, plopping, near-liquid sound, as if three tons of gelatin were moving down the corridor toward her.
<GET BACK INSIDE THE CHAMBER, LOCK THE DOOR> Her body started to move in response to her intent; however, it didn't follow through. Her arm reached for the door, but it stopped in mid-air. It was the numbing scent that had her in its spell.
She half turned. The sound of the approaching creature was noticeably nearer.
Now that she no longer faced her approaching doom, talk overheard at the Wizard's Gate came back to her. This was the CATACOMB's garbage collector. It was so huge that it entirely filled the width and height of the corridor; it digested anything organic in its path. Nothing she had heard, however, warned her of its stupefying scent.
It worked! She moved. Okay Simple actions only.
She wasn't moving fast, but neither was her musty friend
She does get darted again by the thief, only to wake up to him being willing to talk things over with her, in part because she didn't kill him (and in fact bandaged his knife wound) before succumbing to the effects of the poison (she'd improvised a tourniquet, which slipped).
He came relentlessly on. "Should have killed me. I should ... have killed you." His hand reached hers and forced the tourniquet loose. "Both ... too civilized ... for this game."
YOU HAVE BEEN RENDERED UNCONSCIOUS BY A POISON DART. YOU ARE LOGGED OFF CATACOMB FOR 01:30 MINIMUM. YOUR ACCOUNT BALANCE IS: $ 2.21 FOR TODAY $ 13.83 FOR THE GAME $ ??.?? TREASURE BONUS {RESERVED} {CONDITIONAL = 53}
....
The dollar sign on the screen triggered a memory, and for a moment Lunae considered how to get the arm band back from her thief and how to learn its secrets. Then Judith spilled the beans. She filled him in on the unusual logoff message she'd received, even replaying it and the condition code description back from her terminal's local memory. Afterward, she explained her theory about the arm band.
"Angel, this is not how you're supposed to play this game. I'm supposed to kill you; you're supposed to kill me; and we're both supposed to steal each other's treasures."
They make a deal where she gives him the magic treasure in return for his $50 of treasure he was carrying and a guaranteed safe route back, and when she next logs in, she's in a safe place and has a note from him. He's given her $500 instead, enough to pay for the music school she wanted to attend. Browsing the news sites, she learns that he likely made off with over $50,000 in treasure thanks to the teleportation band, and an interview with him implies that he's moving to the protagonist's town, so she'll get a chance to meet him in real life.
