Pop Out: players may remove one of their own discs from the bottom of a column instead of dropping, shifting everything above down.; Pop 10 / Power Up: published variants adding special discs or objectives.; 5-in-a-row on a larger grid: a common informal extension that removes the solved first-pl...
Why people argue about this
People often assume that Pop Out means you can remove your own disc from anywhere in the column, which isn't correct - it specifically refers to removing a disc from the bottom row after dropping another one. The confusion arises because this nuance is not clearly defined or emphasized in most variant rulesets.
