I was a big fan of both Seven Kingdoms titles, but liked the first one better. Now, thanks to Trevor Chan, the game has become open source and is available as 7kaa (and is in the Ubuntu repos). I still recommend buying the game from GOG if only to (hopefully) give Trevor a few more bux, and to get the essential manual.
Everything other reviewers have said about this game still hold true. Linux (and Windows users) can download this game, and then download Arx Liberatis, an open-source new engine for this (really) very good game which uses the data packs from the game. This engine modernizes the game for modern systems, and fixes bugs in the original game. Mac users can still use Arx Liberatis, but they'll have to download the source code and compile it for OSX.
Now that this game has been ported to iOS (Where's Android? Actually, it seems that A-Squared, the developers, are working on an Android version), LOTS more FAQs and pages have been seen on the web. Yes, it's complicated. Yes, while it's easy to get started, you NEED to print out, read, consult, and practically memorize its contents. Read the Lore sections in-game. Keep failing. NOBODY has made a game like this (Darklands, available from GOG.com for the same price, is similar enough that you might check it out if KoDP rings your bell) and possibly, now that it's sold 50K copies for iPad, we might see more games like this one. There's more to Glorantha than just this game, excellent as it is.