Logic Gate Lamp (Off)

A gate on its own does nothing. The lamps stacked above it are its inputs, and the gate compares their on and off states against whatever operation it was built for before deciding whether to fire the wire below. You are not limited to a pair either. Keep stacking lamps on the same gate and it folds all of them into one result, which saves a lot of chained gates on anything more involved than a two-input check. The Steampunker sells the lamps alongside the gates themselves, so a whole circuit comes out of one shop.

Wire hitting a lamp flips it rather than setting it, so the state you place is the state the gate reads until something toggles it. That flip is the closest thing the game has to a NOT gate: put an on lamp where you would otherwise want a negated input and the signal arrives backwards for free. The faulty version is a different animal. Drop one onto a gate, the gate turns blue, and it abandons its printed logic completely.