To get access to all landscapes you'll need the $40-$65 Oxyd-, Per.Oxyd-book. The price is in most cases not the problem, but the ordering itself. In the USA the Dongleware stores are closed and in the german store the aren't able to understand an english order. In addition it's nerve-racking to seek the spell for the damned magic tokens.
To cap it all the codes for accessing managed landscapes change by playing landscape 10 again or reinstallation. Smutty Smurf provided a patch which vanishes these problems into thin air (IBM only, for MAC and ATARI are modified game versions available). It works (like this picture just by pressing any key!) for Oxyd, Per.Oxyd, Oxyd.Extra and Oxyd.Magnum. Download it from this page and you will be able to skip nasty landscapes.