About License: Cross-platform

Traditional licensing requires a customer to make separate purchases of a game for each platform they wish to run it on. For example, purchasing the Mac, Linux, Amiga versions require 3 purchases, each with their own copyright and EULA. However, some companies allow customers legitimate access to all available versions with a single purchase. So that can install it on 3 different platforms using only one purchase.

Note, this is not for cases one purchase entitles many versions (ie: Mac/Windows/Linux/Amiga) but one or more other purchases are required for other versions (ie: separate WiiWare purchase)

2010-12-09
Excluding the "many platforms" cases removes cases where it's technically or commercially not viable to allow all platforms to be included, e.g. PS3 games "require" BlueRay disc, so if you purchase from retail, you'd need to get two or more discs. Digital purchases can be assumed to be more free, but they falter when the systems do not allow granting external "freebies" (e.g. that WiiWare example, I think).

Also, the "all platform license" may very well depend on where you purchase the game, as buying from Steam guarantees you get both Mac and Windows versions of games, but purchasing the same games from retail or other digital distributor does not (unless they can be registered on Steam as well, but not everyone of them can be). Making them all platforms cases with exceptions, which is essentially the same as the many platforms case.