Originally Posted by iamthekiller
Two game modes: Odyssey and Arcade. Odyssey mode is a 27-level guided tour through the Osmos Blobiverse, while Arcade mode allows you to play any level type at your choice of difficulty.
"Arcade mode" is simply odyssey mode with each of the 27 levels on different difficulty levels.
The dev isn't very smart in how it presents it, it's not the same levels, ie a more difficult level of a given type is really a different level. The 47 levels in Mac/PC version are in fact a subset of iPad levels. I haven't unlock all ipad levels but it seems there's 72 levels on ipad and it's really different levels. But also all the 27 levels of Odyssey mode are including in the 72 Arcade levels.