Osmos also has a lot of different and interesting mechanics. For one thing, propelling yourself requires you to eject mass in the opposite direct, which also makes you smaller. There's also antimatter bubbles that you don't want to absorb, a gravity (orbit) mechanic, green "living" bubbles which compete with you for resources, etc.

[space] spawns a small yellow killer bubble. yes, it's possible, but very very hard.

It appears that the yellow killer bubble circumference is proportional to your size, its takeoff vector is the same as your own, and its velocity is a slight multiple of your own.

Ah, that helps a lot. So instead of using your own mass as momentum a la Osmos, you use it as... space-mines =)

I see why you say it's a little bit of Asteroids, now. That sure puzzled me before.