Circuit Flow

Circuit Flow is a puzzle game about rotating wires to get power from a source to a terminal. Tap a tile, it turns 90°. Keep going until the whole path lights up.
It starts easy but gets tricky fast — once the board fills up, half the tiles you see aren't even part of the real path. They're decoys, sitting there looking exactly like the wires you need, and you have to figure out which ones actually matter. Add in obstacles, tiles that are locked in place, and eventually two or three terminals that all need power at once, and it stops being a "quick five minute game" pretty fast.
There's no ending. I didn't put a final level in — it just keeps generating harder boards for as long as you want to play.
You earn coins for solving levels, more if you do it in as few moves as possible, and there's a small bonus for playing on consecutive days. You can spend those coins on hints, extra hearts, or on wire themes that change the colors of your circuit — there's a rainbow one that's probably overpriced but worth it.