The Balloon Dog Puzzle Game, you use the arrow keys, or G, J and Y, to guide the puppy across the universe by having him jump on the safe balloons (green ones with nothing on them).
The yellow balloons are OK, but don't linger on them because they tend to sink. The green balloons with the pointed things sticking up are to be avoided - they puncture the puppy and send him down. The red balloons with arrows explode in the direction they point when the puppy lands on them and may or may not aid him in the direction he is headed.
Anyway, it's fun and more difficult than it appears. Read the documentation for more information.
System Requirements: 100 mHz or faster PowerMac with 16 Megs or more memory running recommended; System 7.5 or greater. Pop! runs on slower machines, but it's less fun. If Pop! seems slow on your machine, try disabling virtual memory. The Shareware version of Pop! will let you play an assortment of 10 of the 87 levels that are available in the registered version.