I liked the online game well enough to buy the full version, which has its own self contained (if slightly lame) story. The different “borbs” (characters) are sort of riffs on character archetypes and the “lumps” are evil invaders from outer space who attacked the borbs’ peaceful town for no apparent reason.
In the paid version it starts off with easy levels which get progressively harder, and you make your way around town (there are different backgrounds and everything for each part of town, it’s pretty cool) and fight bosses along the way.