Wellfall

Every level draws the orb it is asking for at the top of the screen, ringed. Building that orb is the level.

You build it by dropping orbs in and fusing them: two of the same kind that touch become the next one up, eleven rungs from a cold cyan spark to a green giant that barely fits the shaft. Miss, and the well fills past the line and you go again.

Then the next level asks for a bigger one, and tightens something. The walls come in, the roof comes down, the well starts half full, everything turns springy or heavy or slippery. And now and then a bomb falls instead of an orb: it takes out whatever it lands on and blows the rest of the pile apart.

• Twenty-four levels, and every sixth one is a guardian — the door into the next chapter and its own new well. Most people lose those the first time.
• Nothing to read. The goal is drawn, the progress is drawn, and a star is one level beaten.
• Real physics underneath: the pile settles, rolls and betrays you honestly.
• One thumb on a phone, a mouse on a desktop.

Plays in the browser. Nothing to install, nothing to sign up for.