The squeeze
Room only goes one way
Every drop costs space and only a merge returns any. So a run isn't really a score going up, it's a debt you're either clearing or not.
Drop one in, merge it into something bigger, drop the next. Nine creatures deep, Spark to Leviathan, in a jar of moving water. There's only so much room, and merging is the only way to make more.
Pick a spot along the top and let go. A guide line shows you where it lands, which helps right up until it doesn't.
Two of the same meet and become one bigger thing. That is the entire rule, and it will take you a while to get bored of it.
Merging is the only thing that gives space back. Anything you drop that doesn't merge is room you've spent.
There is a dashed line near the top, and resting above it for a couple of seconds ends the run. It fills up faster than it feels like it's filling up.
The squeeze
Every drop costs space and only a merge returns any. So a run isn't really a score going up, it's a debt you're either clearing or not.
The reprieve
Build something big enough and you bank a bomb. You can't spend it when you'd like to — only at the instant the run would otherwise have ended, on whichever one you think is holding the pile up.
Droptide is free, and about as far from a commitment as a game gets.
Open the tab, drop a few, close the tab. Or don't close the tab. It'll be in the same state either way. There is one purchase in it, for the three modes that aren't Tide and three of the four palettes, and the game never asks you about it until you've played them.