Add mechanics
Mechanics in Runner are actions the game performs for you: deal cards, shuffle a deck, assign a role like a judge, reshuffle the discard pile back into the deck. Instead of writing these as rulebook text and trusting players to remember, you attach them to a phase of your game, and they fire automatically when that phase begins during play.
To add one, open the rules panel, select a phase, and click Add Mechanic. Each mechanic has a short configuration form. A deal mechanic, for example, asks which deck to deal from, how many cards, whether to deal to every player or to a zone on the table, and whether the cards land face up. This is where your table layout pays off: a deal mechanic can target a display zone or a market zone you placed in the workbench.
Where you attach a mechanic controls when it runs. A shuffle attached to Start of Game runs once when play begins. A deal attached to a turn step runs every turn for the active player. A common pattern in card games is an initial deal of a full hand at game start, plus a "draw up to" top-up at the start of each turn, so hands refill automatically.
Mechanics are the biggest difference between a digital prototype and a paper one: they remove upkeep. Playtesters spend their attention on decisions instead of administration, which makes feedback about the actual design rather than about whose turn it was to shuffle.