Where
Orbient was basically an entire game about gravity,
Osmos takes a more varied approach. Sure, there's a piece of
Osmos that has a gravity theme, but even in that area you have full control over your "craft," if you can call it that. Each level in
Osmos has a measure for success that is almost always connected to merging your blobbish mass with other blobbish masses. At times this is the only goal, stated simply as, "Become the biggest." Other times, you'll grow in service of a secondary goal, like absorbing other sentient masses in the level. As with another "ambient" classic,
flOw,, your surroundings in
Osmos are fluid and dynamic. Most objects are just in motion, a la
Asteroids, but some have a purpose. Some really great A.I. is at work here, such that smaller orbs (those that can move independently) seem aware of when to run away and when to go on the attack. "Survival of the largest" would be the
Osmos translation of Darwin, and you'll find most levels are a mad scramble to accumulate smaller particles before they become absorbed.
Osmos doesn't conform to what most games present as "modes." A more subtle approach is used in almost everything about this game, which we loved. There are branching paths you will open up through success in earlier levels, and each path features levels with certain rules at play. Purely ambient play is all about gathering a majority percentage of the total mass in that level, without much external pressure. Other paths introduce different gameplay mechanics involving some aggressors that make your life more difficult, and some challenges for you. At least one style of play has you revolving around a large orb that is constantly pulling you closer as you become larger. Each level plays quickly and features several keyboard shortcuts that let you dial the speed up or down as you like. There's enough challenge to keep most players happy for a long while, and there's no doubt that while Osmos isn't strictly speaking a Casual title, it has those great pick-up/put-down qualities that make so-called Casual titles so easy to return to time and time again.
