only drop garbage if there is room

[omenking]

Garbage will not drop until there is room.

Research

This requires game-mechanics research, ask the experts.

• when will garbage not drop?
• is there a delay between next drop or business as usual?

[jon12156]

also see related issue #172

garbage will not drop if there is zero room for it in the visible section of the playfield. That said, it may drop if it can partially (even a fraction of a row) fit in the visible section.
Also consider #108. During this initial drop (spawn) and each subsequent row drop due to stack-lowering of the garbage block, if when it lands it doesn't completely fit itself on the play field, it causes screen shake (and associated shake time where you can't die)

[jon12156]

after a garbage block's initial drop AND landing are complete, another garbage block may enter the screen.