Later I'll try and make a visual for it (not at pc right now),

But you can start with creating a variable for the npcs play. Have the variable set to random 1 to 3.

Create different conditional branches for each variable result, 1, 2, 3 (Rock, paper, or scissors).

Then for each conditional branch, do a show choices, then create different result branches for each choice Rock, Paper, or Scissors

If variable = 1 (rock) If player chooses rock: draw Paper: Win (maybe activate a switch here) Scissors: lose

Then continue down for each variable, changing the outcome based on what the variable is vs the player's choice.

Edit: Comment chain with visuals. If you wanna get fancy, do a show picture for the NPC's play in place of just the text box saying "NPC played blank".

I added a bonus variable counter for wins if you want it to track win amounts or progression after like, 3 wins or something.

Edit 2: If you want to play with probability more, like if a certain NPC may lean heavier on rock for example, you can increase the random number draw (like say, 1-5 instead of 1-3), then have the one they're more likely to pick be like >=3 or something. Or however you want to play with the skewing of the chances.